Samantha "Sammi" Slott is a former main character of Seasons 4 and 5. She is the oldest daughter of Frank Gallagher and Queenie Slott, revealed when sought out by Frank when he needs a liver transplant corroded by his alcoholism. She lives in a trailer in a rundown neighborhood with just her son, Chuckie. Unaware that he's her father upon meeting him, she is sexually attracted to him, but Frank accidentally reveals the truth when she informs him that she cannot give him her liver, as she is not a match. Although intensely enraged at her unintentional supposed moral crime, she quickly accepts him back and becomes his caretaker. Frank explains that his estrangement from her stems from his youthful immaturity when he became a father, his initial desire to abort her, and his uncertainty about how he impregnated her mother. It is not revealed who fathered Sammi's son, Chuckie. Sammi takes the role of main antagonist for season five.
"But I do know that Sammi is all about giving love. After all, she’s been married three times and engaged twelve. I think she’d do anything for her new family." ~ Emily Bergl on Sammi Gallagher. But in season five, she blames Carl for Chuckie being arrested on counts of possession. After she hears about Chuckie getting sent to juvie, the entire Gallagher family turn on Sammi for the remainder of her time with them until she is incarcerated.