Kermit the Frog is puppeteer Jim Henson's most famous Muppet creation, first introduced in 1955. He is the main protagonist of many Muppet projects, most notably as the host of The Muppet Show, and has appeared in various sketches on Sesame Street, in commercials and in public service announcements over the years. Kermit was performed by Henson until his death in 1990. Since then, Kermit has been performed by Steve Whitmire.
Kermit's First Appeared in "S.T.A.R.Y." he talks about Teens and Kids.
In most of his animated appearances, Geo G. voiced him, but in "Son of the Witch" he was voiced by Frank Welker who had previously voiced the character in Muppet Babies. In "Jeremy's 2nd Girlfriend Crushed on", he was voiced by John Viener.
He is used as an example of a Muppet who hasn't sounded the same since Henson's death in "Jeremy's 2nd Girlfriend Crushed on".