Francis “Frank” Gallagher (William H. Macy) is the father of six children. He is a deadbeat alcoholic, drug addict and morally deficient freeloader who relies on his children to barely get by. He also swindles the state welfare system and this type of opportunistic deceit has been learned by his children.
According to Fiona, since Frank refuses to work and most of them are uneducated, the family lives far below the federal poverty threshold for a family their size. Frank did attend college to study psychology, where he met Monica. They had only dated for about 2 weeks before they got married.
Frank bangs almost any available woman, resulting in the births of even more children. For instance, he begins a relationship with Sheila Jackson when he discovers that she gets maximum disability benefits for her agoraphobia.
The children refer to their father as “Frank”. Although Frank pontificates self-righteously about political and social issues, he spends most of his time developing schemes to cheat the system and take advantage of others in order to make money. He pays little attention to his children but can display care and concern for them in drastic circumstances.
In season 4, his liver fails, as the result of his chronic alcoholism. He tracks down his daughter Sammi, and although she is not a match for a liver transplant, she and Sheila go out of their way to arrange Frank’s liver surgery. They find an unlicensed Bangladeshi surgeon willing to do the operation, using a Bangladeshi donor. The surgeon initially asks for $30,000 but when the two women admit they can only pay $26,000, he reluctantly agrees to operate. With money acquired by Sammi from the sale of Sheila’s furniture, along with Sheila’s savings, the cost of the surgery is covered. The surgeon makes off with the money and one of Frank’s kidneys, leaving Frank with his original failing liver. Nevertheless, Frank is supplied with a replacement liver from the emergency room that allows him to continue drinking.
In season 5, a home beer still mishap causes Sheila to leave for good. In episode 9, Frank embarks on a “bucket list” style spree with Bianca, who has advanced pancreatic cancer. They spend Bianca’s last days together and although Bianca’s thrill seeking is too much for Frank, they end up in Costa Rica. After leaving a note for Frank, Bianca commits suicide by walking naked into the ocean. Frank returns home crying and tells Lip and Ian that Bianca has died.
In season 7, the Gallagher kids, except Liam, have had enough and kick Frank out of the house. He “disowns” them and makes a “new” family at a luxurious homeless shelter he created by a scheme, of course. He is defenestrated when the homeless patrons find out he’s been hiding money they earn.
In season 8, Frank will cope with Monica’s death by doing all of the meth she bequeathed to him, then having a midlife crisis where he tries to restart his life as a 21 year old, having realized that Monica was the trigger of his alcoholism and bad parenting. He will become sober, clean his hygiene up, get a real job, a car, and tries to be a more productive member of society.