If you have read any of Dickens's other works or researched this author, you may, then, be familiar with a prevailing social concern of his: the dehumanizing effects of crime. Certainly these effects are evinced in the characters of Oliver Twist. Now, if you wish to compose a thesis on this topic, you may wish to limit your examination to one character if your assignment is an essay. However, if your assignment is a paper, then you will want to analyze several characters.
Oliver Twist is a narrative in which the most depraved villains preside, with the heinous Fagin controlling the others. That he loses all humanity is apparent throughout the novel, most strikingly at the end when, incarcerated and alone in his depravity, Fagin loses his mind. As a metaphor of this transformation, the turnkey asks him,
"Fagin, Fagin! Are you a man?"
"I shan't be one long," he replied, looking up with a face retaining no human expression but rage and terror....
Another character, the murderous bully Sikes, evolves throughout the novel into an absolute monster. Under his control, poor Nancy struggles to retain her humanity, regaining it in her solicitous acts on behalf of Oliver, but falling victim to the band of criminals who will not release her. In contrast to Oliver, his half brother degenerates spiritually until his final end. For a time, Oliver even suffers some dehumanization and he worries that he will never be believed or treated fairly even if he escapes the evil band of thieves who have captured him.