| Year | Title | Role | Notes |
| 1975 | Kojak | Bryan LeBlanc, Mr. Roberts | Episode: "Money Back Guarantee" |
| 1976 | Charlie's Angels | Scott Woodville | Episode: "Charlie's Angels" (Pilot) |
| Doc | Stanley Moss | 7 episodes |
| 1976–1977 | The Mary Tyler Moore Show | Mel Price | 3 episodes |
| 1976 | Phyllis | Mr. Raymond | Episode: "The Wrong Box" |
| 1976–1977 | Rhoda | Dr. Curt Dreiser, George | 2 episodes |
| 1977 | This Is the Life | Harry | Episode: "Undertow" |
| The Tony Randall Show | Cleaver | Episode: "Case: The People Speak" |
| 1977–1983 | M*A*S*H | Major Charles Emerson Winchester III | 131 episodes |
| 1978 | The Paper Chase | Woodrow Tullis | Episode: "An Act of Desperation" |
| 1979 | $weepstake$ | Wally | Episode: "Billy, Wally and Ludmilla, and Theodore" |
| 1981 | CBS Afternoon Playhouse | Peter Stenner | Episode: "Me and Mr. Stenner" |
| 1983 | American Playhouse | Doc | Episode: "The Innocents Abroad" |
| 1984 | The First Olympics: Athens 1896 | William Milligan Sloane | Miniseries |
| 1985 | North and South | Congressman Sam Greene | Miniseries; 6 episodes |
| 1986–1996 | Murder, She Wrote | Howard Deems, Sergei Nemiroff, Aubrey Thornton | 3 episodes |
| 1986 | North and South, Book II | Congressman Sam Greene | Miniseries; 6 episodes |
| 1987–1988 | Matlock | Thomas Baldwin, Arthur Hampton | 3 episodes |
| 1988 | ALF | Flakey Pete | 2 episodes |
| 1989 | The Ray Bradbury Theater | Leonard Mead | Episode: "The Pedestrian" |
| 1990 | CBS Schoolbreak Special | Jack Henderson | Episode: "American Eyes" |
| Married People | Dr. Cashin | Episode: "Term Paper" |
| Wings | Edward Tinsdale | Episode: "A Little Nightmare Music" |
| 1991 | Star Trek: The Next Generation | Timicin | Episode: "Half a Life" |
| 1993 | Jack's Place | Flower Man | Episode: "Forever and Ever" |
| 1994 | The Boys Are Back | George Spivack | Episode: "A Tree Dies in Portland" |
| 1995–2011 | American Experience | Narrator | Voice, 32 episodes |
| 1996 | Cybill | Val | Episode: "Educating Zoey" |
| Poltergeist: The Legacy | Randolph Hitchcock | Episode: "The Twelfth Cave" |
| 1997 | Dr. Quinn, Medicine Woman | Theodore Quinn | Episode: "Farewell Appearance" |
| 1998 | 101 Dalmatians: The Series | VLAD | Voice, episode: "Out to Launch/Prophet and Loss" |
| Ally McBeal | Judge Andrew Peters | Episode: "They Eat Horses, Don't They?" |
| Two Guys, a Girl and a Pizza Place | Mr. Bauer | 13 episodes |
| 1999 | The Angry Beavers | Byron Beaver | Voice, episode: "Kreature Komforts/Oh, Brother?" |
| The Practice | Judge Hollings | Episode: "Infected" |
| The Outer Limits | Reverend Dr. Thomas Tilford | Episode: "The Shroud" |
| 1999–2000 | Love & Money | Nicholas Conklin | 13 episodes |
| 2000 | The Wild Thornberrys | Karroo | Voice, episode: "Luck Be an Aye-Aye" |
| Bull | Gardner Blackstone | 4 episodes |
| The Trouble With Normal | Mr. Harrington | Episode: "Say Cheese" |
| 2000–2002 | Teacher's Pet | Mr. Jolly, narrator, Congressman | Voice, 39 episodes |
| 2001–2002 | House of Mouse | Cogsworth | Voice, 3 episodes |
| 2002 | Arli$ | Eli | Episode: "It's All in the Game" |
| Justice League | Solovar | Voice, episode: "The Brave and the Bold" |
| 2002–2007 | The Dead Zone | Reverend Eugene 'Gene' Purdy | 40 episodes |
| 2003 | Frasier | Dr. Leland Barton | Episode: "Fathers and Sons" |
| Touched by an Angel | Jones | 2 episodes |
| 2003–2006 | Lilo & Stitch: The Series | Dr. Jumba Jookiba | Voice, main role |
| 2004 | Static Shock | Dr. Odium | Voice, episode: "Hoop Squad" |