What is the name of the man who leads the lynch mob at the jail?

The man who leads the lynch mob at the jail is Walter Cunningham.

More precisely, he is Walter Cunningham Sr., Scout's classmate Walter Cunningham Jr.'s father. The mob gathers outside the jail where Tom Robinson is being held before trial. Atticus Finch stands guard, determined to protect Tom from an extrajudicial killing.

The confrontation changes when Scout, Jem, and Dill arrive unexpectedly. Scout recognizes Mr. Cunningham and talks to him about his son, his entailment, and Atticus's help. Her ordinary childlike conversation breaks through the group's collective hostility. Cunningham realizes what he is doing and leads the men away.

Readers sometimes confuse him with Bob Ewell, Tom Robinson's accuser and later attacker. Ewell is central to the novel's violence, but he is not the man who leads this particular jailhouse mob. Walter Cunningham's role is important because it shows both the danger of mob mentality and the possibility that personal recognition can restore an individual's conscience.