- Frank Gallagher: Played by William H. Macy, Frank is the patriarch of the Gallagher family and a recovering alcoholic. He is known for his irresponsible behavior and often relies on his children to support him.
- Fiona Gallagher: Played by Emmy Rossum, Fiona is the oldest Gallagher child and the primary caregiver for her siblings. She is hardworking, responsible, and often struggles to balance her family obligations with her personal life.
- Lip Gallagher: Played by Jeremy Allen White, Lip is the intelligent and sarcastic middle Gallagher child. He is gifted academically but struggles with addiction and often gets into trouble.
- Ian Gallagher: Played by Cameron Monaghan, Ian is the youngest Gallagher son. He is a complex character who comes to terms with his sexuality throughout the series and joins the US Army.
- Debbie Gallagher: Played by Emma Kenney, Debbie is the youngest Gallagher daughter and known for her headstrong and often manipulative personality. She later becomes a teenage mother.
- Carl Gallagher: Played by Ethan Cutkosky, Carl is the mischievous and often violent Gallagher son. He struggles to find direction in his life and later joins the military.
- Liam Gallagher: Played by Brenden and Brandon Sims, Liam is the youngest Gallagher child. He is often neglected by his siblings and suffers from health issues.