| Year | Title | Role | Notes |
| 1993–1996 | The Adventures of Pete & Pete | Artie, the Strongest Man in the World, Mr. Tastee | 11 episodes |
| 1994–1997, 2011, 2022–present | Beavis and Butt-Head | Todd Ianuzzi, Henry, various | Voice, 26 episodes (under the name of Rottilio Michieli from 1994 to 1997) |
| 1995–1999 | NewsRadio | Jack Frost, Junior, Guard | 3 episodes |
| 1996 | Roseanne | Eric | Episode: "Construction Junction" |
| 1997 | Seinfeld | Jack, The Wiz | Episode: "The Junk Mail" |
| 1997–2010, 2025–present | King of the Hill | Kahn Souphanousinphone, Sr. (1997-2010), Ted Wassanasong (2000-2008), Cotton Hill, Joe Jack, Dale Gribble (2025-Present), Additional voices | Voice, 174 episodes |
| 1998 | The Army Show | Cpl. Rusty Link | 13 episodes |
| 1999 | Hercules | Additional voices | Episode: "Hercules and the Aetolian Amphora" |
| 1999–2000 | The Martin Short Show | Himself | Writer63 episodes |
| 2000–2002 | Nikki | Jupiter | Series regular; 41 episodes |
| 2001 | The Angry Beavers | Rikki / Pirate Rats | Voice, episode: "Beavemaster/Deck Poops" |
| 2002 | Home Movies | Coach / FPC Floating Head | Voice, episode: "Shore Leave" |
| 2002–2003 | One on One | Hank | 5 episodes |
| 2003 | Windy City Heat | Ansel Adams | Television film |
| The Making of King of the Hill | Himself | Television documentary |
| 2003–2005 | Carnivàle | Felix "Stumpy" Dreifuss | 24 episodes |
| 2003–2020 | Reno 911! | Big Mike, General Lee | 19 episodes |
| 2004 | Pilot Season | Stewart | Miniseries |
| 2004–2006 | Harvey Birdman, Attorney at Law | Ernie Devlin, Shado the Brain Thief | Voice, 4 episodes |
| 2005 | The Office | Todd Packer | Voice, episode: "Pilot" |
| 2006 | Help Me Help You | Lenny | 2 episodes |
| 2007 | Curb Your Enthusiasm | Charlie | Episode: "The Freak Book" |
| 2008 | 30 Rock | Deutsche Stimme | Voice, episode: "Episode 210" |
| The Riches | Chet Landry | 2 episodes |
| 2008–2018 | The Venture Bros. | Scaramantula, General Treister, Copy-Cat | Voice, 7 episodes |
| 2009 | In the Motherhood | Goose | Episode: "Bully" |
| Bollywood Hero | Jeff Hacker | Episode |
| The Goode Family | Clyde | 2 episodes |
| Hung | Cliff | Episode: "Thith Ith a Prothetic or You Cum Just Right" |
| 2010 | Criminal Minds | Frank Lynch | Episode: "Mosley Lane" |
| 2010, 2016 | Childrens Hospital | Old Timey Psychiatrist / Rex Hilliard | 2 episodes |
| 2011 | Bob's Burgers | Robber | Voice, episode: "Hamburger Dinner Theater" |
| The League | Flanagan the Drug Dealer | Episode: "The Out of Towner" |
| Shameless | Steve's Boss | Episode: "Father Frank, Full of Grace" |
| Mr. Sunshine | Travis | Episode: "Ben and Vivian" |
| Adventure Time | Booboo, Commander in Movie | Voice, episode: "Heat Signature" |
| Rip City | Ronnie | Television film |
| 2011–2013 | The Cleveland Show | Tutor, Dodgers Coach | Voice, 2 episodes |
| 2011–2012 | Kung Fu Panda: Legends of Awesomeness | Mr. Yeung, Snow Leopard | Voice, 2 episodes |
| 2012 | CSI: Crime Scene Investigation | Jeff Levitt, Frank Sinatra | Episode: "It Was a Very Good Year" |
| The New Normal | Farmer Mark | Episode: "Pardon Me" |
| 2013 | Anger Management | Tom | Episode: "Charlie and the Ex-Patient" |
| Newsreaders | Peter Ruby | Episode: "Fit Town, Fat Town" |
| NTSF:SD:SUV | E-Cigarette Smoking Man | Episode: "Extra Terrorist-rial" |
| Brickleberry | Aubrey | Voice, episode: "Tailer Park" |
| Key & Peele | Shoeshine Customer | Episode |
| The Arrangement | Dizzy Pagliouci | Television film |
| 2013–2015 | Sanjay and Craig | Farmer Larry, Announcer, Steve the Pizza Mascot, Cop, Shopper, Additional voices | 7 episodes |
| 2014 | The Spoils of Babylon | Seymore Lunts | 2 episodes |
