Mr White, Mrs. White, Herbert, Sergeant Major Morris, the Stranger who brings the Whites' the 200 pounds.  

The conflict revolves around the use of the monkey's paw and the results of the wishes.  Fate and chance are themes in the story, along with the flaws of man who place a too high value on material possessions.

The point of view of the story is Omniscient Objective, where the reader is left to draw his own conclusions. 

There are many different aspects of this excellent short story that you could focus on to bring out the mystery, horror and the elements of the supernatural. Key to focus on is the way that W. W. Jacobs, in this story, gives us a horrific retelling of the traditional "three wishes" tale that can be found all over the world. The difference between this tale and its many variations is the way that it incorporates terror and suspense in its narration. One key element that makes this story terrifying is the description of the monkey's paw and the way that it is given a life of its own. Note what happens directly after Mr. White makes his wish for money:

A fine crash from the piano greeted the words, interrupted by a shuddering cry from the old man. His wife and son ran toward him.
"It moved," he cried, with a glance of disgust at the object as it lay on the floor. "As I wished it twisted in my hand like a snake."

Note the way in which the sound of the piano is used to foreshadow the disaster that is going to befall the White family. The crash is emotionally jarring, suggesting that something bad will happen. The crash is also surprising, indicating that the money will be provided but in a way that nobody can foresee. Note too the way that the monkey's paw twisted "like a snake." Snakes are creatures that we associate with evil, and so horror is injected through this comparison.

Through this example and many others, mystery, the supernatural and horror are introduced into this excellent tale.

It is to W. W. Jacobs's credit that the reader is horrified by the ending of his story when there are numerous hints that things may not work out for the Whites.

Here are some elements of foreshadowing that misfortune will strike the Whites after they take possession of the monkey's paw that has had a spell put on it by an old Indian fakir:

• The sergeant-major, who shows the paw to the Whites, states that the first owner of the paw had three wishes and the third was for death.
• The old soldier, who has had his three wishes, morosely throws the paw into the Whites' fireplace.
• When Mr. White makes his first wish on the paw, it shakes in his hand, startling him. After he goes to bed, his son Herbert remains in the darkness and gazes at the dying fire. Suddenly, he sees faces in it.

The last face was so horrible and so simian that he gazed at it in amazement. It got so vivid that, with a little uneasy laugh, he felt on the table for a glass containing a little water to throw over it. His hand grasped the monkey’s paw, and with a little shiver he wiped his hand on his coat and went up to bed.

• Mrs. White sees "the mysterious movements of a man" outside their house on the day after Mr. White wishes for two hundred pounds. The man appears to be indecisive as he walks back and forth three times. Finally, he knocks at the door.

"The Monkey's Paw" begins with an epigraph, a short saying at the beginning of a story, novel, play, poem, or chapter that suggests a theme later revealed in the work.  The epigraph of this story is “Be careful what you wish for, you may receive it.” 

In Part One, the story opens with contrasting imagery: outdoors, the weather is described as cold, windy, and rainy, but in the room where the woman knits and the father and son are playing chess, the room is warmed by a fire. 

The wife and husband in the story are archetypes of a long-married couple; the wife is emotional and controlling, and the husband does the wife's bidding, even when he doesn't want to. 

There is irony to be found in Herbert's words when he tell his father "Well don’t break into the money before I come back."  Mr. White has asked for two hundred pounds, and the irony is that the son comes very close to coming back--but doesn't--and not in the way the reader might expect. The money comes to the Whites, but as a death settlement when Herbert is killed at work. 

The author utilizes suspense throughout the story; once the monkey's paw is in the Whites' home, the reader understands that it is just a matter of time before they will begin to receive their three wishes.  The suspense is at its peak when there is a persistent knocking at the door and Mrs. White struggles to unlock it to let in what she believes will be her son, back from the dead.

The most important element of "The Monkey's Paw" is the charm itself. The monkey's paw is the reason the story exists. Without the charm, the story would not have taken place at all. That being said, the paw not only speaks to the plot of the story, it also speaks to the themes of the story (fate/chance and the human condition).

In regards to the first theme (fate and chance), the monkey's paw symbolizes the problems which may exist if one "messes with" fate through taking chances (like believing in charms). The other theme, the human condition, is important in regards to the monkey's paw as well. The hope that the family has in the paw's ability to grant wishes speaks to the trust and distrust the paw brings for different characters.

W. W. Jacobs's short story "The Monkey's Paw" exhibits most of the primary characteristics of horror fiction. First, it involves a series of events that become increasingly disturbing and supernatural in nature. The White family is enjoying a simple evening at home when the story begins. Mr. White and his son, Herbert, are playing chess. Mrs. White comments from the sidelines. They are just enjoying each other's company as they always do.

But when their guest, Sergeant-Major Morris, arrives and tells the story of the monkey's paw, the tone of the evening changes, and the family is soon caught up in the most unexpected of events: the fulfillment of a "wish" in the most horrible way possible. There is a spell on the monkey's paw, and that spell falls heavily on the White family.

Horror stories feature a dark mood with a great deal of tension. "The Monkey's Paw" certainly has this. The moment the sergeant-major takes the monkey's paw out of his pocket, the story's mood changes. Mrs. White is disgusted and draws back. Mr. White and Herbert are curious. The sergeant-major turns pale as he tells the story and drops a horrible line about the first man who owned the paw and wished upon it: "I don't know what the first two [wishes] were, but the third was for death. That's how I got the paw."

From here on, the tension in the story rises as Mr. White obtains the paw and decides what his first wish will be. A sense of foreboding begins when Mr. White wishes for two hundred pounds, and Herbert's gruesome death seems to reinforce the horrific consequences that Sergeant-Major Morris warned about.

Indeed, a horror story is specially designed to provoke such horror, and "The Monkey's Paw" does this well. When Mr. White wishes for Herbert to be alive, readers cannot help but fear the result of that wish, especially when something begins pounding on the front door. Readers join Mr. White in feeling both dread and disgust over the grisly presence that likely waits behind the door. The story suggests that, whatever is there, it is a supernatural abomination that is not meant to walk in this world.

Finally, horror stories delve into the darkest aspects of humanity. The sergeant-major tells the Whites about the fakir who placed the spell on the monkey's paw. Even though he calls him a "very holy man," the nature of the object calls that description into doubt, especially when the wishes are fulfilled in such horrific fashion.

The Whites are a relatively normal family who become caught up in the desire to get money through a manipulation of fate. Even though they do not quite believe in the monkey's paw, they try it out with devastating results. Yet Mrs. White insists that her husband wish again to bring Herbert back from the dead. She is caught up in her grief, of course, but she fails to use her reason and to remember that the paw cannot actually be controlled and will likely bring only terror and pain. Indeed, one of the main morals of "The Monkey's Paw" is the danger of human beings overreaching their limits and falling prey to powers far beyond their control.

The University of Tennessee's William Robinson created a list of elements which look to define the horror story as its own particular genre. W.W. Jacobs's short story, "The Monkeys Paw," fits most of these elements:

The Unexpected: What usually begins in an unassuming environment and ordinary situation turns into something quite bizarre and unexpected. The strange occurrences in the White household begin normally enough as father, mother, and son enjoy an evening together. They are then introduced to the strange, supposedly wish-giving, monkey's paw by Sergeant Major Morris. The inclusion of the talisman introduces a supernatural and unexpected twist to the story. The White family's acceptance of the monkey's paw leads to a dreadful series of events, including Herbert's death when Mr. White gives in to his dark impulses and makes a wish he will later regret.

The Contrast: There is a contrast between the everyday normalcy of life with the strange events which ultimately take place. The Whites live a routine existence, and the morning after the family receives the monkey's paw is like any other as Herbert prepares to go to work and thoughts about the paw are lost. Jacobs writes:

In the brightness of the wintry sun next morning as it streamed over the breakfast table Herbert laughed at his fears. There was an air of prosaic wholesomeness about the room which it had lacked on the previous night, and the dirty, shriveled little paw was pitched on the sideboard with a carelessness which betokened no great belief in its virtues.

Later that day, however, Herbert turns up dead and Mr. White, who had wished for enough money to pay off his house, receives just that amount as a settlement from Herbert's work, where he was killed in a horrible accident.

The Dark Side: In this element there is often a fight between good and evil. In the story, the mother, grief-stricken over the loss of her son, turns to the monkey's paw to bring her son back. She forces her husband, against his better instincts, to wish Herbert alive again. The malevolent product of this wish is later understood by Mr. White when he realizes that his son will return as a hideous zombie after being maimed and buried.

The Mood: The mood in the horror story is usually menacing and dark, with the atmosphere often portrayed in great detail. This element is apparent in the story when Mr. and Mrs. White are expectantly waiting for the return of their son from the dead:

Neither spoke, but lay silently listening to the ticking of the clock. A stair creaked, and a squeaky mouse scurried noisily through the wall. The darkness was oppressive, and after lying for some time screwing up his courage, he took the box of matches, and striking one, went downstairs for a candle.

The Plot: The plot of the story may begin normally, but will contain frightening and unexpected events. The story opens with Herbert and his father playing chess. It is a typical night in the White household until the monkey's paw is introduced, which leads to the bizarre scene in the fire witnessed by Herbert, his death, and his aborted return. In the plot, a main character usually has to face the evil and overcome it. In the end of the story, Mr. White, realizing what is knocking at the door is not really his son, ultimately finds the paw and wishes away the walking corpse. 

Suspense: Suspense is arguably the most important element of any horror story. In "The Monkey's Paw," this suspense is present in the beginning of the story when the Sergeant Major describes the power of the paw, and in the last section of the story as the Whites await Herbert's return from the dead. Mr. White's frantic attempt to wish his son away is particularly suspenseful:

But her husband was on his hands and knees groping wildly on the floor in search of the paw. If he could only find it before the thing outside got in. A perfect fusillade of knocks reverberated through the house, and he heard the scraping of a chair as his wife put it down in the passage against the door. He heard the creaking of the bolt as it came slowly back, and at the same moment he found the monkey's paw, and frantically breathed his third and last wish.

The way to justify the categorization of "The Monkey's Paw" as a horror story is simply to consider what Edgar Allan Poe would call the "effect" of the story; that is, the feeling that is left with the reader after finishing it. The feeling of horror is created mainly by the ending, when someone comes to the door on a cold, dark night and begins knocking. Since White has used his second wish, saying, "I wish my son alive again," he feels sure that is his son knocking. But his son was mangled in machinery and must be a horrible sight. Mr. White knows this because he had to identify the body. His wife doesn't know what her son must look like and insists on opening the door for him. The reader can only imagine what the son must look like. It is the reader's imagination that creates the "effect" of horror and makes this a horror story.