Why does Curley hate Lennie 'Of Mice and Men'?

Answer 1

The book didn't necessarily state that Curley hated Lennie; however, as slim said in the beginning, Curley is like a "bunch of small people piled up". Since Lennie is known as the "big" (size) character in the story, Curley obviously wanted to beat him up.

One of the other reasons could also be his mental disorder (Lennie).

Answer 2

Curley dislikes Lennie because he sees him as a threat or challenge due to his size and strength, which makes Curley feel insecure about his own authority. Additionally, Curley's possessiveness and jealousy of his wife make him suspicious of Lennie and ultimately leads to their confrontation.