Theo Roosevelt Ursarius (Matthew Theodore Bear in one puppet segment) more common known as Teddy is Caillou's stuffed teddy bear and once belonged to Caillou's Daddy Boris and one of the main characters in the children's TV show series Caillou. He is Caillou's stuffed teddy bear and Gilbert and Rexy's best friends and an close friend of Deedee.
He is an character in the show and only talked in the show's puppet segments., discontinued in later installments of the program. He is still seen in Caillou's room. Teddy is sometimes pessimistic but usually is in a good mood and always ready for a big hug. He doesn't like riding in the car, for he gets car sickness.
Teddy was once Boris' stuffed teddy bear when this latter was an child. But after Boris becomes an grown-up, Teddy becomes Caillou's stuffed teddy bear.
He was seen in Caillou's room when he was with Rexy and Gilbert. Caillou then puts Rexy, Teddy and Gilbert in the bed and turns them from cartoon forms into talking puppets.
He appears in Puppet Segments when he, Gilbert and Rexy are turned from cartoon forms into Puppet forms. Teddy was very sick when he dislikes driving car, Gilbert becomes an doctor and Teddy has check-up.
He is voiced by Joey Mazzarino.