
Filmography140 titles
| Year | Title | Character | Age at release |
|---|---|---|---|
| 2026 | Hulk Hogan: Real AmericanSeries | Self | 88 |
| 2025 | Nobody 2Movie | David Mansell | 87 |
| 2025 | Everybody's Live with John MulaneySeries | Self - Willy Loman, Weston Playhouse, Weston, VT, 2010 (Pre-Tape Segment) | 87 |
| 2024 | KnucklesSeries | Chief Pachacamac (voice) | 86 |
| 2024 | Happy's PlaceSeries | Clive | 86 |
| 2024 | Man and Witch: The Dance of a Thousand StepsMovie | The Alchemist | 86 |
| 2022 | WednesdaySeries | Professor Orloff | 84 |
| 2022 | Who Done It: The Clue DocumentaryMovie | Self (archive footage) | 84 |
| 2021 | NobodyMovie | David Mansell | 83 |
| 2021 | The Tender BarMovie | Grandpa Maguire | 83 |
| 2021 | HacksSeries | Larry Arbuckle | 83 |
| 2021 | Queen BeesMovie | Arthur Lane | 83 |
| 2020 | Reunited ApartSeries | Self | 82 |
| 2020 | Stars in the HouseSeries | Self | 82 |
| 2019 | The MandalorianSeries | Commissioner Helgait | 81 |
| 2019 | That Guy... Who Was In That Thing 3: Trek StarsMovie | Self | 81 |
| 2019 | WildchatMovie | — | 81 |
| 2018 | A Million Little ThingsSeries | Christopher Lloyd | 80 |
| 2018 | James Cameron's Story of Science FictionSeries | Self | 80 |
| 2018 | BoundariesMovie | Stanley | 80 |
| 2018 | The ConnersSeries | Lou Vitore | 80 |
| 2018 | A.P. BioSeries | Melvin | 80 |
| 2018 | One by OneMovie | Harvey | 80 |
| 2017 | Going in StyleMovie | Milton Kupchak | 79 |
| 2016 | 50 Years of Star TrekMovie | Self | 78 |
| 2016 | Donald Trump's The Art of the Deal: The MovieMovie | Doc Brown | 78 |
| 2016 | Must See TV: An All Star Tribute to James BurrowsMovie | Self | 78 |
| 2016 | Cold MoonMovie | James Redfield | 78 |
| 2015 | 12 MonkeysSeries | The Missionary (uncredited) | 77 |
| 2015 | Just in Time for ChristmasMovie | Grandpa Bob | 77 |
| 2015 | 88Movie | Cyrus | 77 |
| 2014 | Over the Garden WallSeries | The Woodsman (voice) | 76 |
| 2014 | Sin City: A Dame to Kill ForMovie | Kroenig | 76 |
| 2014 | A Million Ways to Die in the WestMovie | Doc Brown | 76 |
| 2014 | The Real History of Science FictionSeries | Self | 76 |
| 2014 | Blood Lake: Attack of the Killer LampreysMovie | Mayor Akerman | 76 |
| 2013 | Sid the Science Kid: The MovieMovie | Dr. Bonabodon (voice) | 75 |
| 2013 | The Michael J. Fox ShowSeries | Principal McTavish | 75 |
| 2012 | Piranha 3DDMovie | Mr. Goodman | 74 |
| 2012 | Foodfight!Movie | Mr. Clipboard (voice) | 74 |
| 2012 | The Oogieloves in the Big Balloon AdventureMovie | Lero Sombrero | 74 |
| 2012 | Excuse Me for LivingMovie | Lars | 74 |
| 2012 | Dead Before DawnMovie | Horus Galloway | 74 |
| 2012 | Dorothy and the Witches of OzMovie | The Wizard Of Oz | 74 |
| 2010 | Raising HopeSeries | Dennis Powers | 72 |
| 2010 | R. L. Stine's The Haunting HourSeries | Grandpa Walt Montgomery | 72 |
| 2010 | Piranha 3DMovie | Mr. Goodman | 72 |
| 2010 | MagicMovie | Magic (voice) | 72 |
| 2009 | Santa BuddiesMovie | Stan Cruge | 71 |
| 2009 | MeteorSeries | Prof. Daniel Lehman | 71 |
| 2008 | The Tale of DespereauxMovie | Hovis (voice) | 70 |
| 2008 | FringeSeries | Roscoe Joyce | 70 |
| 2008 | Fly Me to the MoonMovie | Amos (voice) | 70 |
| 2008 | Camelot: Live from Lincoln CenterMovie | King Pellinore | 70 |
| 2007 | The Big Bang TheorySeries | Theodore | 69 |
| 2007 | ChuckSeries | Dr. Leo Dreyfus | 69 |
| 2007 | Head CaseSeries | Self | 69 |
| 2007 | The Alan Titchmarsh ShowSeries | Self | 69 |
| 2006 | PsychSeries | Martin Kahn | 68 |
| 2005 | Numb3rsSeries | Ross Moore | 67 |
| 2005 | Masters of HorrorSeries | — | 67 |
| 2005 | Arthur Hailey's DetectiveMovie | Anderson in Launderette | 67 |
| 2004 | The Tony Danza ShowSeries | Self | 66 |
| 2004 | ClubhouseSeries | Lou Russo | 66 |
| 2004 | I DreamSeries | Professor Toone | 66 |
| 2003 | NCISSeries | Joseph Smith | 65 |
| 2003 | Jimmy Kimmel Live!Series | Self | 65 |
| 2003 | TremorsSeries | Dr. Cletus Poffenberger | 65 |
| 2003 | Haunted Lighthouse 4-DMovie | Cap'n Jack | 65 |
| 2002 | Interstate 60Movie | Ray | 64 |
| 2002 | Hey Arnold! The MovieMovie | Coroner (voice) | 64 |
| 2002 | CyberchaseSeries | Hacker (voice) | 64 |
| 2001 | Law & Order: Criminal IntentSeries | Carmine | 63 |
| 2001 | Kids WorldMovie | Leo | 63 |
| 2000 | Malcolm in the MiddleSeries | Walter | 62 |
| 2000 | EdSeries | Burt Kiffle | 62 |
| 1999 | The West WingSeries | Professor Lawrence Lessig | 61 |
| 1999 | Man on the MoonMovie | Self (uncredited) | 61 |
| 1999 | Baby GeniusesMovie | Heep | 61 |
| 1999 | Alice in WonderlandMovie | White Knight | 61 |
| 1999 | My Favorite MartianMovie | Uncle Martin | 61 |
| 1998 | The Animated Adventures of Tom SawyerMovie | Judge Thatcher (voice) | 60 |
| 1998 | The Real BlondeMovie | Ernst | 60 |
| 1998 | The Ransom of Red ChiefMovie | Sam Howard | 60 |
| 1997 | King of the HillSeries | Smitty (voice) | 59 |
| 1997 | AnastasiaMovie | Rasputin (voice) | 59 |
| 1997 | Angels in the EndzoneMovie | Al | 59 |
| 1996 | Spin CitySeries | Owen Kingston (archive footage) | 58 |
| 1995 | Rent-a-KidMovie | Lawrence 'Larry' Kayvey | 57 |
| 1995 | Things to Do in Denver When You're DeadMovie | Pieces | 57 |
| 1994 | The PagemasterMovie | Mr. Dewey | 56 |
| 1994 | Camp NowhereMovie | Dennis Van Welker | 56 |
| 1994 | Radioland MurdersMovie | Zoltan | 56 |
| 1994 | Angels in the OutfieldMovie | Al the Angel | 56 |
| 1993 | Addams Family ValuesMovie | Uncle Fester | 55 |
| 1993 | Dennis the MenaceMovie | Switchblade Sam | 55 |
| 1993 | Fallen AngelsSeries | Continental Op | 55 |
| 1993 | Twenty BucksMovie | Jimmy | 55 |
| 1992 | Dead Ahead: The Exxon Valdez DisasterMovie | Frank Iarossi | 54 |
| 1991 | The Addams FamilyMovie | Uncle Fester | 53 |
| 1990 | Back to the Future Part IIIMovie | Doctor Emmett Brown | 52 |
| 1990 | DuckTales: The Movie - Treasure of the Lost LampMovie | Merlock (voice) | 52 |
| 1990 | The Earth Day SpecialMovie | Emmett Brown | 52 |
| 1990 | Why Me?Movie | Bruno Daley | 52 |
| 1989 | The SimpsonsSeries | Reverend Jim Ignatowski (voice) | 51 |
| 1989 | Back to the Future Part IIMovie | Doctor Emmett Brown | 51 |
| 1989 | The Dream TeamMovie | Henry Sikorsky | 51 |
| 1988 | Who Framed Roger RabbitMovie | Judge Doom | 50 |
| 1988 | Eight Men OutMovie | Bill Burns | 50 |
| 1988 | Roger Rabbit and the Secrets of Toon TownMovie | Self | 50 |
| 1987 | Legend of the White HorseMovie | Jim Martin | 49 |
| 1986 | Amazing StoriesMovie | R. Beanes | 48 |
| 1986 | MiraclesMovie | Harry | 48 |
| 1985 | Amazing StoriesSeries | Professor B.O.Beanes | 47 |
| 1985 | Back to the FutureMovie | Emmett Brown | 47 |
| 1985 | ClueMovie | Professor Plum | 47 |
| 1985 | Street HawkSeries | Anthony Corrido | 47 |
| 1984 | The Adventures of Buckaroo Banzai Across the 8th DimensionMovie | John Bigboote | 46 |
| 1984 | Star Trek III: The Search for SpockMovie | Cmdr. Kruge | 46 |
| 1984 | The Cowboy and the BallerinaMovie | Woody | 46 |
| 1983 | To Be or Not to BeMovie | Capt. Schultz | 45 |
| 1983 | Mr. MomMovie | Larry | 45 |
| 1982 | CheersSeries | Phillip Semenko | 44 |
| 1982 | National Lampoon's Movie MadnessMovie | Samuel Starkman ("Municipalians") | 44 |
| 1981 | The Postman Always Rings TwiceMovie | The Salesman | 43 |
| 1980 | The Black MarbleMovie | Arnold's Collector | 42 |
| 1980 | Semi-ToughSeries | — | 42 |
| 1980 | SchizoidMovie | Gilbert | 42 |
| 1979 | Butch and Sundance: The Early DaysMovie | Bill Carver | 41 |
| 1979 | The Fantastic SevenMovie | Skip Hartman | 41 |
| 1979 | The Lady in RedMovie | Frognose | 41 |
| 1979 | The Onion FieldMovie | Jailhouse Lawyer | 41 |
| 1978 | TaxiSeries | Reverend Jim 'Iggy' Ignatowski | 40 |
| 1978 | Goin' SouthMovie | Towfield | 40 |
| 1978 | Lacy and the Mississippi QueenMovie | Jennings | 40 |
| 1977 | Another Man, Another ChanceMovie | Jesse James (uncredited) | 39 |
| 1976 | The Adams ChroniclesSeries | Tsar Alexandre I | 38 |
| 1975 | One Flew Over the Cuckoo's NestMovie | Max Taber | 37 |
| 1975 | Saturday Night LiveSeries | Self (uncredited) | 37 |
| 1975 | Barney MillerSeries | Arnold Scully | 37 |