Lucy Barker was Benjamin Barker's wife and while he was arrested, she was raped by Judge Turpin, which drove her to attempt suicide by poisoning. Mrs. Lovett tells Sweeney Todd (previously Benjamin Barker) that she had poisoned herself, however she conveniently forgets to add that she survived the attempted suicide. Although she survives, she is left mentally insane from it. After the Judge raped her, he took her daughter, Johanna Barker, as his ward.

During the movie, Lucy wanders as a beggar woman. She meets Anthony and during their brief acquaintance she tells him that Johanna is Judge Turpin's ward. She cannot remember anything from her past and therefore shows no bitterness towards Turpin. Also, more tragically, while she knows Johanna's name, she does not remember the girl as her daughter.

Lucy is also seen wandering around Sweeney's barbershop, her old home, which is a weak insinuation that she does have a bit of memory regarding her past.

Lucy was murdered by mistake by her husband Sweeney Todd "Benjamin Barker" in which he shows extreme remorse and in rage Sweeney Todd kills Mrs. Lovett for lying to him by throwing her in the oven and is last seen dead holding Lucy. She was portrayed by Laura Michelle Kelly in the 2007 film adaptation.