| Year | Title | Role | Notes |
| 1979 | Secret Army | Staff Sergeant Drexler | Episode: "The Execution" |
| 1980 | ITV Playhouse | Tom Phillips | Episode: "Friends in Space" |
| 1981 | The Good Soldier | Jimmy | Television film |
| Goliath Awaits | Bill Sweeney |
| Private Schulz | American Newsreel Commentator | Uncredited voice; episode |
| Code Red | Inspector Ray Allen | Episode: "All That Glitters" |
| 1982 | Hill Street Blues | Phony Cop | Episode: "Some Like it Hot-Wired" |
| 1982–1993 | Cheers | Cliff Clavin | 274 episodes; directed 4 episodes |
| 1983 | Wizards and Warriors | Archie | Episode: "The Dungeon of Death" |
| 1984 | Magnum, P.I. | Walt Brewster | Episode: "The Legacy of Garwood Huddle" |
| 1985 | St. Elsewhere | Cliff Clavin | Episode: "Cheers" |
| The Love Boat | Marty Elder | Episode: "A Day in Port" |
| 1986 | Combat Academy | Mr. Barnett | Television film |
| 1987 | Timestalkers | General Joe Brodsky |
| The Tortellis | Cliff Clavin | Episode: "Frankie Comes to Dinner" |
| 1988 | Small World | Morris Zapp | 6 episodes |
| Mickey's 60th Birthday | Cliff Clavin | Television film |
| 1990 | Walt Disney's Wonderful World of Color | Episode: "Disneyland's 35th Anniversary Celebration" |
| Wings | Episode: "The Story of Joe" |
| The Earth Day Special | Television film |
| Camp Cucamonga | Marvin Schector |
| 1990–1996 | Captain Planet and the Planeteers | Rigger | Voice; 24 episodes |
| 1992 | Nurses | Mr. Hafner | Episode: "Illicit Transfers" |
| 1993 | Bill Nye the Science Guy | Host of Ferns | Episode: “Dinosaurs" |
| 1993 | Moon Over Miami | Norman Rust | Episode: "Farewell, My Lovelies" |
| 1994, 2014 | The Simpsons | Cliff Clavin, CGI Homer Simpson | Voices; episodes: "Fear of Flying", "Treehouse of Horror XXV" |
| 1995 | Murphy Brown | Felix | Episode: "A Rat's Tale" |
| Sister, Sister | Gus Kiamilikimaka | 2 episodes |
| 1996 | Caroline in the City | Mr. Berman | Episode: "Caroline and Richard's Mom" |
| Toy Story Treats | Hamm | Voice; Interstitials |
| 1997 | Happily Ever After: Fairy Tales for Every Child | Hinky | Voice; episode: "The Pied Piper" |
| Sabrina, the Teenage Witch | Bob/Santa Claus | Episode: "Sabrina Claus" |
| The Detectives | Edsel | Episode: "Go West Old Man" |
| 1998 | Remember WENN | Mr. Abernathy | Episode: "And If I Die Before I Sleep" |
| 2000 | Touched by an Angel | Merl | Episode: "Monica's Bad Day" |
| Pigs Next Door | Ike Stump | Recurring voice |
| 2001 | That '70s Show | Glen | Episode: "Holy Craps" |
| The Drew Carey Show | Himself/Various | Episode: "Drew Live III" |
| 2002 | Frasier | Cliff Clavin | Episode: "Cheerful Goodbyes" |
| The Pennsylvania Miners' Story | Thomas "Tucker" Foy | Television film |
| 2003 | 8 Simple Rules | Fred Doyle | 4 episodes |
| 2004–2008 | Made in America | Himself | Host; 97 episodes |
| 2006 | Rodney | Episode: "Celebrity" |
| Mystery Woman: Redemption | Jim Carter | Hallmark movie |
| 2008 | Our First Christmas | Joe Noll |
| 2011 | Melissa & Joey | Arnie | Episode: "A House Divided" |
| 2012 | Matchmaker Santa | George | Hallmark movie |
| 2012–2014 | Drop Dead Diva | Larry Kaswell | 3 episodes |
| 2013 | Bones | Bill Schumacher | Episode: "The Cheat in the Retreat" |
