Gene Siskel (1946-1999) was a film critic who wrote for the Chicago Tribune. He is most well known as the co-host of several incarnations of movie review television programs, such as At the Movies.
He appeared on Sesame Street with Roger Ebert in a Sneak Peek Previews segment in season 22, spoofing their own series. The critics instruct Oscar and Telly on how their thumbs up/thumbs down rating system works. When Telly asks if there could be a thumbs sideways rating, Oscar goads the two men into an argument about whether or not that would be acceptable. The pair were also seen in the celebrity version of "Monster in the Mirror."