Arthur Fleck / Joker
Arthur is a mentally ill man and failed stand-up comedian who feels completely marginalized and abandoned by the system. He has a history of abuse which further drives him to become a villain, having been mistreated by his delusional and mentally ill mother. At the beginning of the film, he is desperately trying to get better by sticking to his medication and routine check-ups. However, when things don't go his way, and one of his coworkers gives him a gun, Arthur begins a descent into madness and villainy. He reaches his tipping point when he finds out that he is adopted and that he was severely abused as a child which has affected his entire life. At this point, he finds empowerment through becoming a psychotic master villain, a vengeful vigilante and unhinged psycho killer. Throughout the film, he vacillates between sweet naivete, and abject evil. This ability to turn on a dime is what makes his villainy so terrifying and disturbing. He tries to maintain a sense of ethics in how he kills and commits violence, hurting only those who exploit and wrong others, but his efforts become inconsistent as he is pushed further and further into madness.
Murray Franklin
Murray is a TV show host and Arthur’s lifelong idol. Arthur frequently watches him on television with his mother and dreams of being on the show with him. Murray is a classic show-business mogul, a snappy and opportunistic showman who likes to tell jokes with mass appeal. In many ways, he is the father figure that Arthur never had, and everything that Arthur is not. Where Arthur is unusual, marginalized, unfunny, and outside the mainstream, Murray is accessible, universally beloved, good at telling a joke, and a staple of the mainstream.
Sophie
Sophie is Arthur’s neighbor and love interest. She is also a struggling single mother who is also greatly affected by the political and economic changes in Gotham. Arthur’s delusions make him believe that he’s in a relationship with her, and this imagined relationship makes Arthur more confident in his own skin. He dreams that Sophie is showing him affection and support, which helps to encourage him, even though this is not actually the case.
Penny Fleck
Penny is Arthur’s adoptive mother who is also mentally ill. She is obsessed with Thomas Wayne and believes that Arthur is hers and Thomas’ son. However, the files at the asylum suggest that this is a complete delusion on her part. When the film starts, Arthur takes care of her and loves her a lot, speaking highly of her everywhere he goes. Once he finds out that she was complicit in his abuse as a child, he turns on her, and descends into disappointment, rage, and madness.
Thomas Wayne
Thomas is a wealthy man in Gotham who is running for mayor. For a brief moment, Arthur believes that Thomas Wayne is his father. He is hated by many in Gotham, mostly the lower class. He speaks out against crimes and poverty in the city, but he does little to help the poor or actually affect change in Gotham. He eventually becomes one of the many people Arthur despises, as he is the epitome of the wealthy elite that have turned their backs on the disenfranchised in society.
Randall
Randall is one of Arthur's coworkers at his job working as a hired clown. Randall is a disparaging and bullying man, who often makes fun of those who are beneath him in status. Even though he tries to sympathize with Arthur after Arthur gets beaten up on the job, he does so by giving Arthur a gun, which only contributes to Arthur's instability.
