Kermit
picture by hrpff
Kermit the Frog of Jim Henson's muppets is a moderate Sentence Game meme with 20 games mentioning him dating back to game 1008. Kermit is stable because of his unique profile compared to other amphibians. Yoda and Kermit are occasionally seen as antagonists, competing for the title of "green character".
At one point, Cthulhu attempted to depose them both. Results were inconclusive.