The longtime companion of Herbert Garrison ever since childhood, Mr. Hat is a puppet with a mind of his own. Though he may seem merely like an ordinary puppet, Mr. Hat has exhibited many signs of being an independent, sentient being, including the ability to drive a truck, beat up Mr. Mackey and spend time in a sauna room with Brett Favre and a bottle of thousand island dressing. It is unknown where exactly his story begins, but it is known he participated in the Vietnam War alongside Mitch Conner shortly before he became involved with a young Herbert Garrison, a relationship that would continue for nearly forty years and grow to define both men.
Mr. Hat is an aggressive, unforgiving racist and member of the Ku Klux Klan, never missing a meeting, and is also a flaming homosexual who longingly admires not only celebrities like Enrique Iglesias but even his own puppetmaster, Mr. Garrison. He also known for being extremely angry and dangerous, threatening to 'smack these little bitches up' in class and telling students to go to hell, despite the students' preference for him over Mr. Twig, Mr. Slave and even at times, Mr. Garrison. During a therapy session, Dr. Jonathan Katz has suggested that Mr. Hat represents Mr. Garrison's subconscious as a result of childhood drama... such as, perhaps, not being molested by his father as a boy.
Mr. Hat has largely retired from teaching when Garrison became the fourth grade teacher, though he briefly came out of hiding to help deal with Eric Cartman's "daddy issues", reconciling with his old friend Mitch Conner. Now located firmly inside Mr. Slave's asshole, Mr. Hat is living out his final days in peace.
- "You go to hell! You go to hell and you die!" (Cartman Gets An Anal Probe)
- "Genetic engineering lets us correct God's horrible mistakes, like German people." (An Elephant Makes Love to a Pig)
- "Don't apologize for me to that spearchucker!" (Chef Goes Nanners)
- "Boy, that Enrique Iglesias can sure gyrate his hot ass around." (The Entity)
- "Dammit Mitch, you're asking questions that shouldn't be answered!" (201)
- ”With genetic engineering we can correct all of God’s horrible mistakes… like German people.”
- Cartman Gets An Anal Probe (s01e01)
- Weight Gain 4000 (s01e02)
- Big Gay Al's Big Gay Boat Ride (s01e04)
- An Elephant Makes Love to a Pig (s01e05)
- Death (s01e06)
- Pinkeye (s01e07)
- Tom's Rhinoplasty (s01e11)
- Cartman's Mom is a Dirty Slut (s01e13)
- Cartman's Mom is Still a Dirty Slut (s02e02)
- Summer Sucks (s02e08; unseen but oft-mentioned)
- Chef Aid (s02e14)
- Gnomes (s02e17)
- South Park: Bigger, Longer & Uncut
- Two Guys Naked in a Hot Tub (s03e08)
- Chinpoko Mon (s03e10)
- Cartman Joins NAMBLA (s04e06)
- Cherokee Hair Tampons (s04e07)
- Chef Goes Nanners (s04e08)
- Fourth Grade (s04e12)
- The Entity (s05e11)
- The Death Camp of Tolerance (s06e14)
- 200 (s14e05)
- 201 (s14e06)
When the player is inside Mr. Slave's asshole trying to retrieve and defuse the Snuke that was to destroy the town, a spooge and poop-drenched Mr. Hat can be discovered, and will add the player on Facebook, though he makes no posts of his own.
- Mr. Hat was based on a puppet used by Trey Parker's kindergarten teacher, believed by many to be "High Hat".
- Trey Parker has stated that Mr. Hat's retirement symbolized the series' shift from "surreal comedy" to "commentary on current events".