Bert

Bert is a golden yellow Muppet created by Jim Henson. He was on the TV show "Sesame Street". He's Ernie's roommate. 
Character.
Even though Bert is a grumpy, he is still sometimes happy. He's yellow with a single eyebrow called a unibrow, and had a vertical striped shirt (compared to Ernie's which is horizontal). He looks like a banana.
History.
Bert first appeared in the test episodes of Sesame Street in 1969, with his uni brow never moving, and a little more tame. Then later in the years starting in Season 3 of Sesame Street, Bert can move his uni brow up and down. Starting in 1997, he was funnier and nicer but still grumpy. Bert has known to be changed nine times.
Ernie.
Ernie is Bert's brother and roommate. And is the more clumsy and funny guy. He was first seen the same day Bert first was seen. He was voiced by Jim Henson until his death in 1990.