Stewie Griffin

Stewie Griffin is a character in the television comedy "Family Guy". 
Overview.
He is the youngest child of Lois and Peter Griffin. He has two older siblings, Meg and Chris. They are an American family, although Stewie is the only one in his family with a British accent. Seth MacFarlane, is the man responsible for voicing (imitating) and creating the voice for Stewie Griffin. Seth said in an interview that Stewie's voice was inspired by that of Rex Harrison's voice.
Stewie is known for his evil scheme-plotting. During the earlier seasons of Family Guy, Stewie often planned on killing Lois, however, this has since stopped. Stewie built his own time machine that is stored in his room. In the time machine, he has gone to places such as Leonardo da Vinci's house, Poland during the beginnig of World War 2, and even traveled back to the 1st of January 1999 (the first ever episode of Family Guy).
Stewie is often with his stuffed teddy bear called Rupert. 
With Stewie being a baby, only a few main characters can actually understand him. The characters that can understand him include: Brian Griffin and Chris Griffin. There is much debate over which characters in "Family Guy" can understand Stewie. In an interview, the shows creator Seth MacFarlane said that everyone can understand him, but they ignore him or just think to themselves "oh how cute" when he talks. 
However, at the 2011 Comic-Con panel, he would say that Brian always hears Stewie, and more recently so does Chris, but the writers usually try to have Peter, Lois, and Meg not hear him. 
Once Stewie leaves the house, the question of who can hear him depends on the story. MacFarlane also states that these rules can be broken for the sake of comedy, so this usually changes from one episode to another.