There are two common misconceptions regarding the lovable yellow pigeon-loving paperclip-collecting character from Sesame Street.
The first is that he is gay. Jim Henson Productions have always denied this; Ernie and Bert are room-mates, nothing more. No homosexual implications have ever been written into these characters.
The second is that his name is spelt 'burt'. Bert is spelt b-e-r-t. If you are here from Google, chances are you are looking for a "Bert Is Evil" website. It can be found at http://www.spacecat.com/bert/bert.htm. You may wish to note that Dino Ignacio, the original author, has pulled the original site (http://www.fractalcow.com/bert/) and encourages mirrors to close as well, saying that the joke has just gone too far.
Bert was originally performed by Frank Oz, and is now sometimes performed by Eric Jacobson. (When Henson died, Steve Whitmire took over playing both Kermit and Ernie). Muppet fans might like to check http://www.toughpigs.com/extrarecast.htm for re/casting information.