Leonard
Leonard is the protagonist, a man whose wife has been raped and murdered in a traumatic incident. He walked in on it happening and lost his memory after hitting his head while trying to set her free. Ever since, he has had short-term memory loss, which prevents him from learning new information. He has to use photographs and tattoos on his body to remember what he is doing every day and that he is searching for his wife's killer.
Leonard is smart and scrappy in spite of his condition. He is determined and loyal to his wife's memory, single-minded in his desire to reverse the trauma he has suffered. In many ways, he is like a protagonist of an old film noir—tortured by inner demons, but brave and gritty nonetheless, looking to survive however he can.
Teddy
Teddy is a dirty cop who is using Leonard's condition for his own nefarious reasons. He pins Leonard's wife's murder on guys that he himself wants taken out, and Leonard follows through with it, as he has no recollection of what he has already done. In demeanor, Teddy is affable and wise-cracking, and seems more like an endearing sidekick than a villainous mastermind. But underneath his friendly attitude is a malevolent and manipulative mind.
Natalie
Natalie is a bartender who is dating a drug dealer, Jimmy Grantz. She helps Leonard find the information he needs in order to get his revenge on the man who killed his wife, but she also messes with him when she wants to, manipulating him to keep herself safe from another drug dealer, Dodd. She is sweet and vulnerable in moments, taking care of Leonard, but heartless and cruel at others, made ruthless by her hard-knock life.
Burt
Burt is the front desk clerk at the Discount Inn where Leonard is staying. He profits from Leonard's condition by checking him into multiple rooms in order to get him to pay extra, but, compared to many of the other characters, seems not to be an outright bad man.
Jimmy Grantz
Jimmy Grantz is a drug dealer that Teddy wants dead. In order to kill him, Teddy convinces Leonard that Jimmy is his wife's killer, so Leonard kills him.
Dodd
Dodd is a violent drug dealer who goes after Natalie after Jimmy is killed.
