Bear (Also known as Bear In The Big Blue House) is, well, a bear. He has a big blue house and a show about his big blue house called Bear In The Big Blue House, which was named after him.
Bear doesn't like to share his history, but it is presumed that sometime in his life, he met Treelo, Pip and Pop, Ojo, Baby Bear and Tutter in the episode "Inviting Friends Over" where he invited them over to his Big blue house. They became friends and they are the 73rd most dangerous organization in the UnUniverse. They are the Elmo Gang's rivals. Elmo absolutely HATES Bear.
Bear's friends got killed or killed themselves all except Baby Bear (his second in command) throughout the show, leaving Bear and his second in command remaining.
He also possesses the ability to fall with style. In the series finale of his show, he committed suicide by doing so leaving Baby Bear in charge.
Bear is very bossy. Taking cues from Adolf Hitler, Bear is a dictator. He bosses around his gang members with his second in command Baby Bear and forces them to do whatever he says. (They usually do. ^_^) However, he despises criminals like terrorists (save for Hitler) or hunters, and will kill them with his favorite gun, the AK-47. He eats honey, although it isn't as interesting.