Candy is acutely aware of his condition, and is constantly preoccupied with the thought that he will soon be fired. Inevitably, this makes him feel different from the other workers at the ranch, who at least have sufficient health and youth to be able to change their destinies. Candy's condition also provides the spur for him to jump at the chance to be part ofGeorge and Lennie's dream of owning their own ranch.

Crooks is also lonely and isolated. As the sole Black man on the ranch, he's set apart from the others quite literally, forced to live in his own little shack. Crooks confesses that he's lonely, but given the predominant racial prejudice of the age, there's nothing he can do about it. He can engage in superficial conversation with the other men, but that's about as far as it goes. The racial barriers between himself and the others are simply too great for him to be able to forge meaningful connections with the guys in the bunkhouse.

As the only woman on the ranch, Curley's wife is about as lonely and as isolated as it's possible to be. Though much better off than Candy, and with the white privilege denied to Crooks, she's still all alone in the world. Trapped in a marriage that seems less than happy, and with unfulfilled dreams of movie stardom, Curley's wife is so lonely that she often hangs around the ranch hands, engaging in conversation and sexually provocative behavior.

In Steinbeck's celebrated novella Of Mice and Mice, Candy, Crooks, and Curley's wife are depicted as powerless outcasts who experience isolated, lonely lives on the ranch. Candy's age and disability are the primary factors that influence his feelings of isolation. Candy is by far the oldest worker on the farm and is missing his right hand. Given his age and disability, Candy has been reduced to the role of swamper. Candy recognizes that he is no longer useful on the ranch and understands that it is only a matter of time before he is let go.

Candy's inability to perform manual labor makes him somewhat of an outcast because he spends the majority of the day cleaning the bunkhouse while the men work outside. He cannot keep up with the younger workers and has little in common with them. Candy's only companion is his "ancient dog," which Carlson shoots because it is useless and stinks. After Candy loses his dog, he desperately attempts to become partners with George and Lennie.

Crooks is isolated and lonely because he is the only Black man on the ranch and suffers from racial discrimination. Unlike the other white workers, Crooks is prohibited from sleeping in the bunkhouse and participating in certain social activities. Crooks is forced to live by himself in a small room attached to the barn. Crooks spends the majority of his leisure time alone and is excited when Lennie and Candy enter his room. As a victim of racial discrimination, Crooks is voiceless and cannot defend himself when Curley's wife threatens him. Although Crooks is a proud man and capable worker, he lacks social interaction and resents being discriminated against.

Curley's wife is lonely and isolated because she is the only woman on the ranch and is married to a possessive, insensitive man. Curley's wife had dreams of moving away and being in show business but settled for marrying Curley, who is an insecure, domineering husband. Curley's wife feels stifled by her husband's possessive nature and seeks companionship by flirting with the workers. However, the workers view her as a "tart" and fear that they will lose their jobs if they interact with her. Before Lennie accidentally breaks her neck, Curley's wife expresses her feelings of isolation and loneliness by saying,

Why can't I talk to you? I never get to talk to nobody. I get awful lonely … You can talk to people, but I can't talk to nobody but Curley. Else he gets mad. How'd you like not to talk to anybody?

Candy is isolated in that after the loss of his hand he is unable to work alongside the other men and is reduced to the role of swamper. Once his dog has been shot Candy has little else to live for and is desperately lonely. He is powerless and afraid of the future. He does not go into town with the other men, and sees the inclusion in George and Lennie’s dream as the only way out.

Crooks is isolated because of his race, his disability and his deep mistrust of others. He is physically separated from the other men and has his own room in the barn. His crooked back means that like candy he has limited social or work contact with the other men as he tends the horses. His loneliness forces him to acquiesce when Lennie tries to talk to him. Crooks withdraws his request to be part of Lennie and George’s dream after Curley’s wife puts him in his place. His understandable suspicions and fears about how others treat him return and he cannot see beyond the prejudice he has always experienced.

Curley’s wife is the only woman on the ranch and has no-one who will talk to her – including her husband. Her sexuality isolates her from the other characters. She is bored and lonely, but her attempts to engage the attention of the men on the ranch only serve to push them further away from her. She has already given up on her dream of a better life as a movie star and appears to hang her hopes on any man who will listen, as Lennie appears to.

Almost all of the characters deal with loneliness and isolation to some degree in Steinbeck's novella. The two characters who could be considered the loneliest, however, are Crooks and Curley's wife. For a brief time Candy is also quite lonely.

Crooks is the black stable buck on the ranch. He is also partly crippled after being kicked by a horse. Because he's a black man on a ranch dominated by white men he is the victim of both racism and segregation. He is usually not allowed in the white bunkhouse and the one time he is welcome he is involved in a fight, presumably over race. Candy describes the scene:

"They let the nigger come in that night. Little skinner name of Smitty took after the nigger. Done pretty good, too. The guys wouldn’t let him use his feet, so the nigger got him. If he coulda used his feet, Smitty says he woulda killed the nigger. The guys said on account of the nigger’s got a crooked back, Smitty can’t use his feet.” 

Crooks, Lennie, and Candy each suffer from situations that still cause discrimination today: race, mental disability, and age. In addition, Crooks and Candy both have physical handicaps.

Crooks is black and so is shunned by the other ranch hands, who won't share the bunk house with him. They tell him he "stinks," and he is forced to sleep in trough of straw off the harness room of the barn. (He has made the room his own, showing his intelligence with his books.) He spends a good deal of time alone because the other men don't much want to be associated him, and he has learned to accept being lonely. Curley's wife intimidates and humiliates him with the threat of a lynching. Crooks also has a bad back (the source of his nickname) from an injury, which doesn't help him to be accepted.

Lennie is mentally disabled. Since he often doesn't understand what is going on, it is difficult for him to be included in the other men's activities. In addition, George shelters him and tries to keep him apart from the others so that no trouble starts. His being alone is a danger too, as the story shows.

Candy is aging and missing a hand. His chief companion is his old dog, but Carlson shoots the dog because it is blind, smells bad, and is a nuisance in the bunk house. Candy fears he will be fired and left alone to die when he gets too old to work.

Today we have more understanding and compassion for people in the situation of these three men, and legal protections are in place that at least attempt to safeguard people from discrimination.

Candy is considered an outcast on the ranch due to his age and handicap. Unlike the other workers on the farm, Candy is much older and past his prime. He also lost his hand in a farming accident, which has affected his ability to be productive. Similar to his old dog, Candy is becoming less and less useful. He fears that he will eventually be fired and forgotten.

Lennie is considered an outcast because of his low intelligence and dependence on George. Unlike the other men on the farm, Lennie is mentally handicapped, which affects his relationship with the other workers on the ranch. He struggles during conversations because of his lack of social skills and understanding, which further alienates him from the other workers. Lennie's dependence on George also affects his status as an outcast. He is not independent enough to take care of himself and relies on George's intellect and compassion. There are times throughout the novel where Lennie is excluded from the group and left on the ranch while the workers go into town.

Crooks is considered an outcast because he suffers from racial discrimination. Crooks is the only African American worker on the ranch and is forced to live by himself. He is excluded from the bunkhouse, which makes him a lonely, angry man. In a conversation with Lennie, Crooks resents the fact that he is a victim of racial prejudice. He wishes to be included and treated equally but is forced to live an isolated life because of the color of his skin.

The characters of Candy, Lennie, and Crooks are all considered outcasts, in one way or another, in Steinbeck's novel Of Mice and Men.

First, Candy is considered an outcast given that he has simply outworn his ability to function as a worker on the farm. This is mirrored by the fact that his dog is put down for being too old. Candy can be seen in the same way which the dog is: useless and beyond help. The other ranchers' insistence that the dog needs to be put down, based upon his uselessness. Candy recognizes the fact that, one day, he will be seen as useless and discarded as well. Therefore, he is considered an outcast given his uselessness (though the men do not admit it yet--it is coming).

Lennie is an outcast given his diminished mental capacity. His presence on the ranch would not be allowed if George was not there to look out for him and insure that he did what was expected. The fact that he is an outcast is also seen when the men go after him (after he murders Curley's wife) instead of protecting him (as they would if he were a true member of the ranchers' family).

Lastly, Crooks is seen as an outcast for two reasons. First, Crooks is black. Therefore, he is not regarded as having the same worth as a white worker. Second, Crooks has been injured. His ability to perform the duties expected of him have been reduced. Given that he had dedicated his life to the ranch is the only reason he has been allowed to stay.

Loneliness is a theme that runs like a thread through the entire story and is a quality shared perhaps by most of the characters. Migrant workers are often men who have no roots, who drift from place to place to survive and have little stability in their world.

In Candy's case, isolation and loneliness stem partly from the disability caused by his having lost a hand. But his elderly age may be an even more important factor. His dog is his best friend—hence, his extreme reluctance to have the dog put down, even though it's obvious that the animal is suffering and that euthanizing him is the most humane option.

The dream of having one's own homestead is a kind of beacon in the night to George, Lennie, Candy, and Crooks—a solution to their displaced status, even in a world where instability and rootlessness are normal and expected. Each of these men is the Other for a different reason: Lennie because of his developmental disability, George because he isn't free to lead an independent life and must take care of Lennie, Candy because of his age, and Crooks because of his race. The dream of living "off the fat of the land" is alluring but mythical. It represents salvation to these men who wish to escape their isolation and to bond with others who have similar problems. Because of age and a physical handicap, Candy is at least as alone as George, but George's youth gives him more to look forward to even after the tragic conclusion of the story.

Candy could be considered lonely after the death of his dog. Before that he seems relatively happy and, in fact, is quite gregarious in chapter two when George and Lennie first enter the bunkhouse of the ranch. He goes on about the other characters and describes the Boss, Slim, Crooks, Curley and Curley's wife. He even gossips with George, telling the story about the glove on Curley's left hand which is full of vaseline so he can keep "that hand soft for his wife."

It is not until chapter three that Candy's life turns lonely. Carlson, a laborer on the ranch, believes that Candy's dog is too old and decrepit. He suggests that Candy shoot it to put it out of its misery. Candy can't do it and, because Slim gives Carlson the approval, the man takes Candy's dog and kills it. Obviously, the dog was Candy's best friend and the loss throws him into depression. Steinbeck describes Candy right after the men hear the shot that kills the dog:

For a moment he continued to stare at the ceiling. Then he rolled slowly over and faced the wall and lay silent. 

In Of Mice and Men, Curley’s wife and Crooks represent loneliness and isolation in terms of gender and race, respectively. Curley’s wife also symbolizes dependence through her idleness. She does not even have a name, is the only female person on the ranch, and does not have a job to do. Wholly dependent on her vain, insensitive husband, she wanders around the ranch. The refuge she sought in marriage, to a man she has just met, does not fulfill her desire to escape her humdrum life. Her loneliness drives her to confide in Lennie, leading him to the fatal error of believing they are friends.

Crooks, in contrast, is a hard-working man who lives apart from the other ranch hands because of his race. The ranch living accommodations are segregated so he cannot bunk with the other hands. However, this separation also gives him a measure of privacy that the others lack and that he values. This aloofness is accentuated when Lennie walks in uninvited; Crooks tells him that he “ain’t wanted,” just as Crooks himself is not wanted, “Because I’m black.”

Steinbeck wrote “Of Mice and Men” during the 1930s at a time when significant social and economic problems where arising, prompted by the Great Depression, which forced the general workforce of America to become itinerant workers. As a result the characters of the novella live limited existences dominated by the loneliness of a repetitive cycle of earning a large enough “stake” so that they can spend it in a “cat house”, where they can drink “whisky” and “play cards”.

Crooks is excluded from the rest of society in his own “bunk” as a result of the oppressive violence and prejudice he has been the victim of. Experiencing such a plight has resulted in him retiring behind a façade of aloofness. This can be seen by the proud way in which he takes care of his bunk, “the room was swept and fairly neat”, in stark contrast to the bunk houses of the other ranch workers. When actually faced with the presence of others, Lennie and Candy, he gains a large amount of self confidence, which encourages him to try to counter the intrusion of Curley’s Wife, “you got no call foolin’ aroun’… causin’ trouble”. Of course, this is highly out of character and it demonstrates how unusual it is for him to find himself in the company of others.

Similar to Crooks, Curley’s Wife also experiences extreme exclusion from society. However, in her case, it is her gender and her husband that are the obstacles in her search for companionship. This is because, as was the characteristic prejudice towards women at that time, the other characters are suspicious of her and they fear that because of her they might “get canned”. Consequently, she is attracted to Lennie and she devises a complex arrangement to ensure that she could safely be alone with him in the barn. When she gets the chance to talk to him, the words pour out of her in a “passion of communication”. In addition, the interaction reveals a compassionate side of her, which her separation was concealing, when she consoles Lennie after he has killed the puppy, “don’t you worry non’”.

The whole novel Of Mice and Men is filled with lonely characters.  Candy is lonely as an old man with no family and no secure future.  George is lonely for companionship because he takes care of Lennie and because he is a migrant worker and never has the time to cement friendships or relationships.  Curley and his wife are alienated from each other, and Curley from the whole ranch it would seem.  Crooks is physically lonely, as no one socializes with him, and there is no one else from his race or culture to socialize with.

Curley's wife and Crooks do not, by themselves, then, symbolize loneliness.  Rather, the whole novel portrays the all-encompassing loneliness of a broken society in the depths of the Depression, and of those who are most vulnerable in it.  This includes Curley's wife and Crooks, but it also includes almost everyone else in the story.

I do think they are both symbols of loneliness in one simple way: they are each a representative of an under-represented social class.

Curley's wife is the only woman in the entire novel who has a speaking part. Look at her name! She doesn't even receive an identity of her own. I think this shows that she represents an independent or individual or isolated experience.

Crooks, likewise, is the only black man on the ranch. He has to deal with being separated from the rest of the men because he smells different. He even physically has a different sleeping location. He too is isolated, representing loneliness. 

Are you sure that there is supposed to be anything beyond the simple fact that they are really lonely and act really lonely?  I do not really think they are supposed to symbolize anything -- at least not in the way that the farm that Lennie and George dream of symbolizes freedom or Candy's dog represents what happens to people who outlive their usefulness.

To me, Curley's wife and Crooks just ARE lonely, as you say.  They show how loneliness affects people -- Crooks tries to destroy Lennie's dream even though he really wants to share in it, Curley's wife acts in ways that will get the men in trouble even though she really wants their company.  But I do not see them as symbols.  I see them more as characters who are defined by their loneliness.

There is not enough evidence in the story that would substantiate that Slim is a lonely man. This is, if you use the word "lonely" to the same extent as it is applied to Curley's Wife, Candy, and Crooks. If you compare the four, Slim would definitely stick out as the one who is the least lonely of them all. In fact, Slim seems to have achieved a level of self-sufficiency which may be the result of a life which, in his eyes, is somewhat satisfactory.

To answer this question with more accuracy, I would bounce back to the two main characters, and focus mostly on George, and not Lennie. Why? Because Lennie, in his mind of a simpleton, knows and trusts that George will always be his companion. He makes plans that include George, feels safe with him, and has developed a bond that is strong enough for him to know that George is not going anywhere.

Yet, what about George's own needs? He does not see Lennie under the same light as Lennie sees him. George is basically dragging around life with Lennie because he is compassionate enough to help him. However, he lives in consistent anxiety and stress hoping and praying that Lennie's rough ways will not cause another accident, or another accidental death-which is worse. He worries about what Lennie says and does all the time. He knows that Lennie is a burden, but it is one that George sees himself carrying for the rest of his life. This is not exactly what he envisions for himself as a person, but it is what he has come to accept.

Therefore, George is the loneliest of them all. He does not fit in with the ranch hands as well as the others fit in with each other, he has to live with the burden that is Lennie, and he has to look out for himself because he has nobody else.

In the end, when Lennie accidentally kills Curley's wife, George did the ultimate act of mercy by shooting Lennie in order to spare him a slow death in the hands of a vengeful lynch mob. When Lennie dies, we can feel deeply how lonely George truly is in this world, and we can also realize how lonely he has always been.

In Of Mice and Men, Curley's wife, Crooks, and Candy demonstrate that they are lonely. First, Curley's wife is a flirt. She flirts with the men on the ranch because she is lonely. Curley often accuses the other men of being inappropriate with his wife. He accuses Slim of improprieties with his wife. All the men insists that Curley keep his wife home:

The men all side with Slim and tell Curley to keep her at home.

Curley's wife is so lonely until she reaches out to Lennie who is mentally unstable. That is how she loses her life. 

Crooks is the only black man on the ranch. He is lonely and ostracized from the rest of the ranch hands. He has to live in isolation from the others just because he is black. When the others play games, he is not invited to play along. When Lennie wanders in Crooks's room, Crooks allows him to stay because Crooks is so lonely. Even though Crooks discourages Lennie from dreaming about owning his own farm one day, Crooks seems to enjoy Lennie's company. 

Candy is another lonely character in the novel. He is so lonely until he invites himself to be a part of George's and Lennie's dream of owning their own farm and farmhouse one day. Candy asks if he con contribute his money and become a part of their dream:

He is sweetly hopeful of joining Lennie and George on their dream farm, offering to contribute his savings of $350 to buy the farm.

Candy feels as if he is becoming old and useless around the ranch. He realizes that one day he will not be needed, just like his old dog who is shot by one of the ranch hands:

Candy is the old, disabled ranch hand who is helpless to stop the shooting of his dog and who knows that he too will be banished when he is no longer useful.

No doubt, Candy desires to belong. That is why he invites himself to become part of George's and Lennie's dream of owning their own farm and farmhouse one day. Sadly enough, when George has to shoot Lennie, Candy knows the dream is over, but he pleads with George to carry out the dream:

“You an me can get that little place cant we George? You an me can go there an live nice cant we George?” 

Truly, Candy is a lonely man who needs George as much as Lennie did.