Crooks is the lonely stable buck on the ranch who by virtue of the fact he is a negro is forced to live separately from the bunk house. We first hear of him (and the origin of his name) when Candy mentions to George upon his arrival that the stable buck is a nigger,
"Yeah, Nice fella, too. Got a crooked back where a horse kicked him." (p.22)
Whilst the use of the derogatory label 'nigger' is an example of authentic language from that time, it still gives us an idea of the low esteem in which Crooks is held. This is reinforced by Candy mentioning that Crooks bears the worst of the boss's temper, and his fond recount of the last Christmas party where one of the workers "took after the nigger" (p.22) and a fight ensued.
Lennie's meeting with Crooks is preceded by a long description of Crooks's living quarters, and highlights the lonely existence of this social outcast. Yet importantly Crooks is characterized as someone of spirit, living separately but proudly,
...for Crooks was a proud, aloof man. He kept his distance and demanded that other people kept theirs. His body was bent over to the left by his crooked spine, and his eyes lay deep in his head, and because of their depth seemed to glitter with intensity. (p.62)
"Crooks could leave his things about, andbeing a stable buck and a cripple, he was more permanent than the other men,and he had accumulated more possessions than he could carry on his back."