William "Bill" Sikes is a fictional character and one of the main antagonists in the 1838 novel Oliver Twist by Charles Dickens. Sikes is a malicious criminal in Fagin's gang, and a vicious robber and murderer. Throughout much of the novel Sikes is shadowed by his “bull-terrier” dog Bull's-eye.

Edward "Monks" Leeford is a fictional character and one of the main antagonists in the 1838 novel Oliver Twist by Charles Dickens. He is actually the criminally-inclined half-brother of Oliver Twist, but he hides his identity. Monks' parents separated when he was a child, and his father had a relationship with a young woman, Agnes Fleming. This resulted in Agnes' pregnancy. She died in childbirth after giving birth to the baby that would be named Oliver Twist.