Thog is a 9½-foot tall blue monster. His size may make him imposing, but he has a sweet and gentle disposition.
He first appeared as one of Cosmo Scam's evil henchmen in the 1970 Christmas special The Great Santa Claus Switch, partnered with a green monster named Thig. In a 1971 Dick Cavett Show appearance, Jim Henson referred to Thog as a large Frackle, though Thog is not generally considered part of that group of monsters.
As a full-bodied Muppet, combined with his droopy, friendly face, Thog was especially well-suited to dance numbers, on television and in stage shows, and he was partnered with several famous ladies over the years. He appeared on stage with Nancy Sinatra as part of her stage show in 1971, and in the unfinished TV version Movin' with Nancy: Nice 'n' Easy (1973). Also in 1973, Thog was featured prominently in "Oh Babe What Would You Say," with Julie Andrews in The Julie Andrews Hour. He also had a featured number in the 1974 pilot The Muppets Valentine Show, singing and dancing with "Real Live Girl" Mia Farrow.
On The Muppet Show, he could be seen in the opening theme (alongside Timmy Monster, Sweetums, and two of The Mutations) from season two on. Thog appeared in a number of segments including: as a "dangerous" animal in episode 110; reprising "Oh Babe What Would You Say," this time with Kaye Ballard, in episode 123; detonating a blast for "School's Out" in episode 307; and demolishing a desert research facility in Loretta Swit's number, "I Feel the Earth Move," in episode 502.
As first revealed in behind-the-scenes photos and trailers, Thog was present in The Muppets; his first appearance in a Muppet production for more than three decades. Here, Thog (rebuilt by Jim Kroupa) appears to be much larger than he was originally; in one scene, he briefly gets stuck going through the arches during the rehearsal for "The Muppet Show Theme" recreation, causing Thog to have to walk in front of them.
- Jerry Nelson from The Great Santa Claus Switch (1970) to The Muppet Show (1980)
- Tyler Bunch in The Muppets (2011)
- Although still voiced by Jerry Nelson, Steve Whitmire performed in the Thog suit at least twice: in episodes 307 and 502.
- The Great Santa Claus Switch
- The Dick Cavett Show
- Movin' with Nancy: Nice 'n' Easy
- The Julie Andrews Hour ("Oh Babe What Would You Say?")
- The Muppets Valentine Show ("Real Live Girl")
- The Muppet Show
- "The Muppet Show Theme" (Seasons 2-5)
- Episode 108: Paul Williams (Blackout)
- Episode 110: Harvey Korman (Circus sketch)
- Episode 123: Kaye Ballard ("Oh Babe, What Would You Say?")
- Episode 212: Bernadette Peters ("Take a Little One Step")
- Episode 307: Alice Cooper ("Once a Year Day," "School's Out")
- Episode 312: James Coco ("Short People")
- Episode 502: Loretta Swit ("I Feel the Earth Move")
- Julie Andrews: One Step Into Spring
- The Muppet Movie ("The Rainbow Connection" Finale)
- The Muppets
- Muppets Most Wanted
- The Muppet Show Book (1978)
- The Comic Muppet Book (1979)
- It's The Muppet Show! (1979)
- Muppets at Sea (1980)
- Fozzie's Big Book of Sidesplitting Jokes (1981)
- Two for the Show (1982)
- Jim Henson's Muppet Show Bill (1982)
- Bo Saves the Show (1982)
- The Phantom of the Muppet Theater (1991)
- The Muppet Show Comic Book: Meet the Muppets (2009)
- The Muppet Show Comic Book: Pigs in Space (2009)
- The Muppet Show Comic Book: On the Road (2010)
- Muppet Snow White (2010)
- The Muppets Character Encyclopedia (2014)