Stewie Griffin

Stewie turns one in "Chitty Chitty Death Bang" and celebrates a birthday again in "Chap Stewie". He is highly literate and quotes pop culture from long before his birth, yet also shows infant traits: he talks to his teddy bear Rupert, cannot use a toilet and is fooled by peekaboo. MacFarlane has said the character represents an infant's helplessness seen through adult eyes. Stewie builds advanced machines, including time machines, a teleporter, robots, clones and a device for travelling between universes, and he uses them against Lois because she keeps unwittingly wrecking his plans. He achieves matricide and world domination in "Stewie Kills Lois" and "Lois Kills Stewie", but the events prove to be a simulation, and he shelves those ambitions. In "The Big Bang Theory" he learns he descends from Leonardo da Vinci on Lois's side.

MacFarlane based Stewie's accent on the English actor Rex Harrison, in particular his performance in the 1964 film My Fair Lady, with some influence from Mr Burns of The Simpsons. He has said more than once that he would want David Hyde Pierce to play Stewie in any live-action version. Stewie's head is shaped like a rugby ball; a cutaway in "Stuck Together, Torn Apart" shows it being flattened when he hits the ceiling, though flashbacks in "Chitty Chitty Death Bang" show the shape from birth. Several commentators, including author Chris Ware, have noted that Stewie resembles Jimmy Corrigan, the title character of Ware's 1995 graphic novel. Fox maintains the character is original, and MacFarlane said in 2003 that he had never seen the comic.

The writers began hinting at Stewie's sexuality with one-off gags in the second season, in episodes such as "Chick Cancer" and "We Love You, Conrad". MacFarlane planned a third-season finale in which Stewie came out following a near-death experience. The show's cancellation stopped that, and an episode titled "Queer Is Stewie?" was produced but never aired. Since then MacFarlane has kept the character deliberately ambiguous, saying the flexibility gives the writers more freedom and makes more sense for a one-year-old. In "Turkey Guys", "Send in Stewie, Please" and other episodes he appears about to come out before being interrupted.

MacFarlane won a Primetime Emmy for Outstanding Voice-Over Performance for voicing Stewie, and an Annie Award in 2006 for his work in "Brian the Bachelor". IGN named Stewie the best Family Guy character in its top 25 list, and Wizard magazine rated him the 95th greatest villain of all time. Entertainment Weekly placed him 45th in its 2010 ranking of the previous twenty years' top 100 characters. Hal Boedeker of The Orlando Sentinel praised the character. The Road to episodes built around Stewie and Brian are among the show's highest-rated and best-reviewed instalments.

Which characters can understand Stewie has never been settled. MacFarlane has said that everyone can basically hear him but ignores him or finds him cute. At a 2011 Comic-Con panel he said Brian always hears Stewie and Chris increasingly does. The writers try to keep Peter, Lois and Meg from hearing him, except in "Leggo My Meg-O". Outside the house it depends on the story, and the rules can be broken for a joke. In "Stewie's First Word" Stewie concludes that people understand him only when he wants them to, which happens when he feels strong emotion.