Gabe Ugliano is Percy Jackson's lazy, disrespectful and abusive scumbag of stepfather in Percy Jackson and the Olympians: The Lightning Thief. He serves as a supporting antagonist of the novel and it's movie adaption of the same name.
Gabe is lazy and fat and tells his stepwife (Percy's mother, named Sally in the books) to do everything for him, like for example, get him his beer out of the fridge instead of doing it himself (which may be why he became so abusive). After which she does retrieve his beer to him, but he then slaps her across the buttocks. His stepson, Percy ,is disgusted by this and asks him not to do such a thing, but Gabe refuses to listen to Percy. After the attack on Percy at the museum, Percy came home to talk to his mother about what happened, but Gabe rudely interrupted his stepson's talk by remarking that "she was servicing me and my friends". Percy retaliated by calling him a "bald-headed freak", angering him and making him attack Percy, but Percy's friend and protector named Grover stopped him and knocked him out and the three escaped his wrath.
Later, the disappearance of Percy, Grover and Percy's mother reached out on TV and Gabe told a lot of lies about what happened at his house, saying that "due to the fact that Percy became an alcoholic and drug dealer, he knocked out Gabe and kidnapped his mother and his friend". It is unknown whether the authorities believed his story or not. However, as Percy is never seen being interrogated by the police after he and his mother returned, it's likely they didn't believe Gabe.
At the end of the film, Percy's mother kicked Gabe out due to his abusive nature. He goes to the fridge, but there is a paper note and a lock on it by Percy saying "do not open". Gabe angrily ignores it, smashes the fridge open to get his beer and finds Medusa's severed head in there which kills Gabe by turning him into a statue when Gabe foolishly looked into the eyes. In the book, Sally sold his remains at the Soho Art Gallery.
This is MY house! You show some respect!
~ Gabe reprimands Percy to assure his abusive dominance after he was told to respect Percy's house.
Woman! Where's my beer!?
~ Gabe orders Sally around when he walks into the apartment.
Can't you see she's servicing me and my friends?!
~ Gabe interrupts Percy when he arrives at the house to save his mother.