| Year | Title | Role | Notes |
| 1974 | The Law | Murray Stone | Television movie |
| 1975 | The Law | Murray Stone | 3 episodes |
| 1975 | Fear on Trial | Saul | Television movie |
| 1975 | Medical Story | Dr. Joe Dempsey | Episode: "Waste Land" |
| 1975 | The Legend of Valentino | Jack Auerbach | Television movie |
| 1976 | The Keegans | Lieutenant Marco Ciardi | Television movie |
| 1976 | Visions | Joe Morris | Episode: "Two Brothers" |
| 1977 | Rhoda | Mike | 2 episodes: "Rhoda Likes Mike"; "The Weekend" Nominated—Primetime Emmy Award for Outstanding Lead Actor for a Single Appearance in a Drama or Comedy Series |
| 1976–1977 | Delvecchio | Sergeant Dominick Delvecchio | 21 episodes |
| 1978–1983 | Taxi | Alex Reiger | 114 episodes Primetime Emmy Award for Outstanding Lead Actor in a Comedy Series (1981, 1983) Nominated—Golden Globe Award for Best Actor in a Television Series – Musical or Comedy (1978–1982) Nominated—Primetime Emmy Award for Outstanding Lead Actor in a Comedy Series (1979–1980, 1982) |
| 1979 | Sooner or Later | Bob Walters | Television movie |
| 1979 | The Halloween That Almost Wasn't | Count Dracula | Television movie |
| 1980 | Marriage Is Alive and Well | Herb Rollie | Television movie |
| 1980 | The Last Resort | Dr. Zegelman | Episode: "Zegelmania" |
| 1981 | The Robert Klein Show | Unknown | Television movie |
| 1983 | Lights: The Miracle of Chanukah | Unknown | Television movie |
| 1985 | Detective in the House | Press Wyman | 6 episodes |
| 1985 | First Steps | Dr. Jerrold Petrofsky | Television movie |
| 1985 | Brotherly Love | Ben Ryder/Harry Brand | Television movie |
| 1988–1992 | Dear John | John Lacey | 90 episodes Golden Globe Award for Best Actor in a Television Series – Musical or Comedy (1988) Nominated—Golden Globe Award for Best Actor in a Television Series – Musical or Comedy (1989) |
| 1988 | The Great Escape II: The Untold Story | Capt. David Matthews | Television movie |
| 1989 | PBS NOVA | Himself (Host/Narrator) | Episode: "The Hidden City" |
| 1990 | She Said No | Martin Knapek | Television movie |
| 1994 | Betrayal of Trust | Dr. Jules Masserman | Television movie |
| 1996 | Caroline in the City | Ben Karinsky | Episode: "Caroline and the Comic" |
| 1997 | Color of Justice | Sam Lind | Television movie |
| 1997–1998 | George and Leo | Leo Wagonman | 22 episodes |
| 1999 | Rocky Marciano | Al Weill | Television movie |
| 2000 | Welcome to New York | Dr. Bob | Episode: "Dr. Bob" |
| 2001 | Family Law | Daniel Bonner | Episode: "Security" |
| 2002 | Philly | Rabbi Nathan Wexler | Episode: "The Curse of the Klopman Diamonds" |
| 2003 | Law & Order: Special Victims Unit | Dr. Judah Platner | Episode: "Mercy" |
| 2003 | Regular Joe | Baxter Binder | 5 episodes; Also Producer |
| 2003 | Street Time | Shimi Goldman | Episode: "High Holly Roller" |
| 2003 | Law & Order: Criminal Intent | Ben Elkins | Episode: "Pravda" |
| 2003 | Who Killed the Federal Theatre | Narrator | Television movie |
| 2005 | Family Guy | Himself (voice) | Episode: "Blind Ambition" |
| 2006 | Tom Goes to the Mayor | Prisoner (voice) | Episode: "Spray a Carpet or Rug" |
| 2006 | Studio 60 on the Sunset Strip | Wes Mendell | Episode: "Pilot" |
| 2009 | American Dad! | Rabbi (voice) | 2 episodes |
| 2005–2010 | Numb3rs | Alan Eppes | 114 episodes |
| 2010 | Warehouse 13 | Isadore Weisfelt | Episode: "Secret Santa" |
| The Whole Truth | Judge Wright | Episode: "Judicial Discretion" |
| 2011–2012 | Damages | Bill Herndon | 14 episodes |
| 2012 | The Good Wife | Judge Harrison Creary | Episode: "Here Comes the Judge" |
| 2013–2015 | Maron | Larry Maron | 4 episodes |
| 2014 | Sharknado 2: The Second One | Ben | Television movie |
| 2014–2015 | Forever | Abraham "Abe" Morgan | 22 episodes |
| 2014 | Small Miracles | Mort | 4 episodes |
