Although she does mention that her uncle had been arrested, the first character to defy the status quo in Fahrenheit 451 is Clarisse. She exhibits her defiance through her innocence and curiosity. She informs Montag that she and her family sit around and talk. This is a seemingly meaningless practice, but it is something which most people in this society do not engage in. That being said, her family also defies the status quo and they are all eventually eliminated.
Montag is the next character in the story to rebel. His rebellious drive began with his conversations with Clarisse. As he continues to think and react in light of his new quest for knowledge and freedom, he elicits the help of Faber. Then, Montag brings Faber into the mix and as Faber helps Montag, he too becomes an enemy of the State.
Granger and the book people are also defiant characters. In fact, their defiance requires them to live on the outskirts of society.