Stewart "Stewie" Gilligan Griffin is the flamboyant and eccentric son of Peter and Lois Griffin Stewie, equipped with his teddy bear and his laser gun, has, on several occasions, almost single handedly taken over the world and he seems to be obsessed with world domination and matricide.
Stewie is well-spoken, with an advanced vocabulary, an upper-class British accent and an ambiguous sexual orientation. He refers to Peter often as 'The Fat man' and his mother by her given name, Lois.
On the show, Stewie engages in extreme violent or criminal acts, including robbery, carjacking, loan sharking, forgery, and killing off many minor characters. The characters he kills off are for reasons such as anger, jealousy, and grudges he holds. Stewie's mastery of physics, mechanical engineering, and firearms are at a level of science fiction. He has constructed advanced fighter-jets, a mind control device, a weather control device, robots, a time machine, a shrinking pod, a teleportation device, and more. Stewie employs these to deal with the stresses of infant life such as teething pain, and his hatred of broccoli or to kill his mother. Stewie also shows infant-like tendencies such as pretending his tryke is an actual vehicle. Stewie's ability to move objects of greater weight than himself is not surprising to other characters, nor is his ability to perform martial arts or retrieve firearms from hammerspace.
He made jokes about Brian killing a dog, Brian asks him how he'd feel if he had killed another baby. He merely replied by telling him he's killed seven, acting as if it was no big deal. He also tries to get children to drink poison.
Stewie, like his mother, has a masochistic personality. This was revealed when Lois spanked Stewie for destroying her pearl necklace. Stewie later confided to his teddy bear that he found that he enjoyed suffering from such pain, and unsuccessfully went out of his way to provoke Lois several times in the episode into spanking him again. He even had a day dream in which he was tortured by Lois, who was clad in a dominatrix outfit. Stewie comes home with his right arm pulled out of its socket, Brian then stuffs Stewie's mouth with paper so he can't yell for Lois. Brian then painfully but successfully puts Stewie's arm back in its socket. After the act, Stewie notes that he won't say if he liked it or not. Peter enters the kitchen drunk and angry, forcing his family to line up to get cigar burns. After Stewie is burned, he returns in a disguise in hopes to get burned again. he claims he plays choking games with Rupert.
Early in the series he was portrayed as being completely obsessed with world domination and killing Lois. It was revealed that after Stewie's birth, the doctor found a map of Europe with plans to bomb its capitals inside Lois. Stewie's favorite meal is cut green beans, Atkins friendly potato sticks arranged in order of size, from large to small, and a Scooby-Doo yogurt with Shaggy's eyes scratched out. He still wants to kill Lois and take over the world but those traits have taken a back seat, although in select episodes Stewie has exhibited some of his more sociopathic traits, such as aggressively shooting Brian in the leg.
Despite all of Stewie's evil traits he did genuinely care about Brian. he revealed that he considered Brian to be his only friend and the only person in the entire world that he cared about.
When Brian was killed by a car, Stewie's devastation over Brian's death caused him to be cold and nasty towards Vinny, a replacement family dog until Vinny told him that he understood what he was going through due to the death of his own previous owner. After that, Stewie bonded with Vinny.
- Stewie Griffin will guest star with Brian Griffin in Winnie the Pooh: Jurassic Jumble.
- Stewie Griffin will be a cameo appearance in Pooh's Adventures of The Fairly OddParents: Channel Chasers.
- Stewie Griffin will gust star with Brain Griffin in Series Finale in Winnie the Pooh goes Back at the Barnyard.