| — | Untitled Lani Pixels Project | Grandpa (voice) |
| 2025 | Nobody 2 | David Mansell |
| — | Meteor | Prof. Daniel Lehman |
| — | Amazing Stories: The Movie I | Professor (archive footage) |
| — | The Movers | |
| 2024 | Knuckles | Chief Pachacamac (voice) |
| 2024 | Self Reliance | Dennis Walcott |
| 2024 | Man and Witch: The Dance of a Thousand Steps | The Alchemist |
| 2024 | Guns & Moses | Sol Fassbinder |
| 2023 | STILL: A Michael J. Fox Movie | Dr. Emmet L. Brown (archive footage) (uncredited) |
| 2023 | Nandor Fodor and the Talking Mongoose | Dr. Harry Price |
| 2023 | Camp Hideout | Falco |
| 2022 | Spirit Halloween: The Movie | Alex Windsor |
| 2022 | Tankhouse | Buford |
| 2022 | Who Done It: The Clue Documentary | Self (archive footage) |
| 2021 | Nobody | David Mansell |
| 2021 | The Tender Bar | Grandpa Maguire |
| 2021 | Expedition: Back to the Future | Self |
| 2021 | Next Stop, Christmas | Ticket Agent/Conductor |
| 2021 | Queen Bees | Arthur Lane |
| 2021 | Senior Moment | Sal Spinelli |
| 2021 | The Center Seat: 55 Years of Star Trek | Self |
| 2021 | King Lear | King Lear |
| 2020 | Reunited Apart | Self |
| 2020 | Stars in the House | Self |
| 2019 | The Mandalorian | Commissioner Helgait |
| 2019 | Dr. Jack & Mr. Nicholson | Self |
| 2019 | The Haunted Swordsman | The Black Monk |
| 2019 | That Guy... Who Was In That Thing 3: Trek Stars | Self |
| 2018 | A.P. Bio | Melvin |
| 2018 | A Million Little Things | Christopher Lloyd |
| 2018 | The Conners | Lou Vitore |
| 2018 | Boundaries | Stanley |
| 2018 | James Cameron's Story of Science Fiction | Self |
| 2018 | Making a Killing | Lloyd Mickey |
| 2018 | ReRUN | George Benson (old) |
| 2017 | Going in Style | Milton Kupchak |
| 2017 | Muse | Bernard Rauschen |
| 2017 | The Sound | Clinton Jones |
| 2016 | I Am Not a Serial Killer | Mr. Crowley |
| 2016 | 情系斯波克 | Commander Kruge (archive footage) |
| 2016 | Donald Trump's The Art of the Deal: The Movie | Doc Brown |
| 2016 | Cold Moon | James Redfield |
| 2016 | 50 Years of Star Trek | Self |
| 2016 | Must See TV: An All Star Tribute to James Burrows | Self |
| 2015 | 12 Monkeys | The Missionary |
| 2015 | 12 Monkeys | The Missionary (uncredited) |
| 2015 | 12 Monkeys | Zalmon Shaw / The Missionary |
| 2015 | Back in Time | Self |
| 2015 | Just in Time for Christmas | Grandpa Bob |
| 2015 | 88 | Cyrus |
| 2015 | Back to the Present: The Special | |
| 2015 | Doc Brown Saves the World | Emmett Brown |
| 2015 | The Boat Builder | Abner |
| 2015 | Keith Lemon's Back t'Future Tribute | Self |
| 2014 | A Million Ways to Die in the West | Doc Brown |
| 2014 | Sin City: A Dame to Kill For | Kroenig |
| 2014 | Over the Garden Wall | The Woodsman (voice) |
| 2014 | Zodiac | Harry Setag |
| 2014 | Blood Lake: Attack of the Killer Lampreys | Mayor Akerman |
| 2014 | The Real History of Science Fiction | Himself |
| 2014 | Pirate's Code: The Adventures of Mickey Matson | Grandpa Jack |
| 2014 | The One I Wrote for You | Pop |
| 2014 | Buenas noches | Self |
| 2013 | The Michael J. Fox Show | Principal McTavish |
| 2013 | Sid the Science Kid: The Movie | Dr. Bonabodon (voice) |
| 2012 | Piranha 3DD | Mr. Goodman |
| 2012 | Foodfight! | Mr. Clipboard (voice) |
| 2012 | Dead Before Dawn | Horus Galloway |
| 2012 | The Adventures of Mickey Matson and the Copperhead Conspiracy | Grandpa Jack |
| 2012 | The Oogieloves in The Big Balloon Adventure | Lero Sombrero |
| 2012 | Los Ilusionautas | Professor (voice) |
| 2012 | Dorothy and the Witches of Oz | The Wizard Of Oz |
| 2012 | Excuse Me for Living | Lars |
| 2012 | Last Call | Pete |
| 2012 | Anything but Christmas | Harry |
| 2012 | The Narrative of Victor Karloch | Victor Karloch |
| 2012 | Cadaver | Cadaver |
| 2012 | Say It Ain't Solo | Himself |
| 2011 | Love, Wedding, Marriage | Dr. George |
| 2011 | The Chateau Meroux | Nathan |
| 2011 | The Witches of Oz | The Wizard of Oz |
| 2011 | InSight | Shep |
| 2011 | Il était une fois… Vol au dessus d'un nid de coucou | |
| 2011 | Adventures of Serial Buddies | Dr. Von Gearheart |
| 2010 | Piranha 3D | Mr. Goodman |
| 2010 | R. L. Stine's The Haunting Hour | Grandpa Walt Montgomery |
| 2010 | Snowmen | The Caretaker |
| 2010 | Tales from the Future | Self |
| 2009 | Santa Buddies | Stan Cruge |
| 2009 | Jack and the Beanstalk | Headmaster |
| 2009 | Meteor | Prof. Daniel Lehman |
| 2009 | Call of the Wild | 'Grandpa' Bill Hale |
| 2009 | Knights of Bloodsteel | Tesselink |
| 2009 | Live from Studio Five | Self |
| 2009 | Looking Back to the Future | Self |
| 2009 | The Macabre World of Lavender Williams | Lester (voice) |
| 2008 | Fringe | Roscoe Joyce |
| 2008 | The Tale of Despereaux | Hovis (voice) |
| 2008 | Fly Me to the Moon | Amos (voice) |
| 2008 | Camelot: Live from Lincoln Center | King Pellinore |
| 2007 | The Big Bang Theory | Theodore |
| 2007 | Chuck | Dr. Leo Dreyfus |
| 2007 | Flakes | Willie |
| 2007 | Head Case | Self |
| 2007 | The Alan Titchmarsh Show | Self |
| 2006 | Psych | Martin Kahn |
| 2006 | Valerie on the Stairs | Everett Neely |
| 2006 | A Perfect Day | Michael |
| 2006 | Looking Back at the Future | Himself |
| 2005 | Numb3rs | |
| 2005 | Masters of Horror | |
| 2005 | Bad Girls from Valley High | Mr. Chauncey |
| 2005 | Stacked | Harold March |
| 2005 | Arthur Hailey's Detective | Anderson in Launderette |
| 2005 | Here Comes Peter Cottontail: The Movie | Seymour S. Sassafras (voice) |
| 2005 | VM Show Vol. 2 | Dr. Emmett Brown (archive footage) (uncredited) |
| 2004 | The Tony Danza Show | Self |
| 2004 | Admissions | Steward Worthy |
| 2004 | Car Crash: The Delorean Story | Himself |
| 2004 | I Dream | Professor Toone |
| 2004 | Clubhouse | Lou Russo |
| 2003 | NCIS | Joseph Smith |
| 2003 | Tremors | Dr. Cletus Poffenberger |
| 2003 | Merry Christmas Space Case | Narrator (voice) |
| 2003 | The Haunted Lighthouse | Cap'n Jack |
| 2002 | Interstate 60 | Ray |
| 2002 | Hey Arnold! The Movie | Coroner (voice) |
| 2002 | Cyberchase | Hacker (voice) |
| 2002 | Wish You Were Dead | Bruce |
| 2002 | The Big Time | Doc Powers |
| 2001 | Law & Order: Criminal Intent | Carmine |
| 2001 | Wit | Dr. Harvey Kelekian |
| 2001 | When Good Ghouls Go Bad | Uncle Fred Walker |
| 2001 | On The Edge | Attorney Bum (segment "Happy Birthday") |
| 2001 | Kids World | Leo |
| 2001 | Chasing Destiny | Jet James |
| 2001 | Space Case | Narrator (voice) |
| 2000 | Malcolm in the Middle | Walter |
| 2000 | Ed | Burt Kiffle |
| 2000 | Convergence | Morley Allen |
| 1999 | Man on the Moon | Self (uncredited) |
| 1999 | The West Wing | Professor Lawrence Lessig |
| 1999 | Baby Geniuses | Heep |
| 1999 | Alice in Wonderland | White Knight |
| 1999 | My Favorite Martian | Uncle Martin |
| 1999 | It Came From the Sky | Jarvis Moody |
| 1999 | The Emperor's Treasure | Lord Imaru (voice) |
| 1998 | The Real Blonde | Ernst |
| 1998 | The Animated Adventures of Tom Sawyer | Judge Thatcher (voice) |
| 1998 | The Ransom of Red Chief | Sam Howard |
| 1997 | Anastasia | Rasputin (voice) |
| 1997 | King of the Hill | Smitty (voice) |
| 1997 | Quicksilver Highway | Aaron Quicksilver |
| 1997 | Angels in the Endzone | Al |
| 1997 | Dinner at Fred's | Dad |
| 1997 | Changing Habits | Theo Teagarden |
| 1997 | Completely Cuckoo | Himself |
| 1996 | Spin City | Owen Kingston |
| 1996 | Spin City | Owen Kingston (archive footage) |
| 1996 | The Right to Remain Silent | Johnny Benjamin |
| 1996 | Cadillac Ranch | Wood Grimes |
| 1995 | Things to Do in Denver When You're Dead | Pieces |
| 1995 | Rent-a-Kid | Lawrence 'Larry' Kayvey |
| 1995 | Mr. Payback: An Interactive Movie | Ed Jarvis |
| 1995 | Deadly Games | Jordan Kenneth Lloyd |
| 1994 | The Pagemaster | Mr. Dewey |
| 1994 | Angels in the Outfield | Al the Angel |
| 1994 | Camp Nowhere | Dennis Van Welker |
| 1994 | Radioland Murders | Zoltan |
| 1994 | In Search of Dr. Seuss | Mr. Hunch |
| 1994 | The Making of 'The Pagemaster' | Mr. Dewey - Host |
| 1993 | Addams Family Values | Uncle Fester Addams |
| 1993 | Dennis the Menace | Switchblade Sam |
| 1993 | Twenty Bucks | Jimmy |
| 1993 | Fallen Angels | Continental Op |
| 1992 | Dead Ahead: The Exxon Valdez Disaster | Frank Iarossi - Exxon |
| 1992 | T Bone N Weasel | Weasel |
| 1991 | The Addams Family | Uncle Fester |
| 1991 | Suburban Commando | Charlie Wilcox |
| 1991 | Back to the Future | Emmett Brown |
| 1990 | Back to the Future Part III | Emmett Brown |
| 1990 | DuckTales: The Movie - Treasure of the Lost Lamp | Merlock (voice) |
| 1990 | Why Me? | Bruno Daley |
| 1990 | The Secrets of the 'Back to the Future' Trilogy | Dr. Emmett Brown (archive footage) |
| 1990 | The Earth Day Special | Dr. Emmett L. Brown |
| 1989 | Back to the Future Part II | Emmett Brown |
| 1989 | 辛普森一家 | Reverend Jim Ignatowski (voice) |
| 1989 | The Dream Team | Henry Sikorsky |
| 1988 | Who Framed Roger Rabbit | Judge Doom |
| 1988 | Eight Men Out | Bill Burns |
| 1988 | Track 29 | Henry Henry |
| 1988 | Roger Rabbit and the Secrets of Toon Town | Self |
| 1987 | Walk Like a Man | Reggie Shand / Henry Shand |
| 1987 | Legend of the White Horse | Jim Martin |
| 1986 | Amazing Stories | R. Beanes |
| 1986 | Miracles | Harry |
| 1985 | Back to the Future | Emmett Brown |
| 1985 | Clue | Professor Plum |
| 1985 | Amazing Stories | Professor B.O.Beanes |
| 1985 | Street Hawk | Anthony Corrido |
| 1984 | Star Trek III: The Search for Spock | Cmdr. Kruge |
| 1984 | The Adventures of Buckaroo Banzai Across the 8th Dimension | John Bigboote |
| 1984 | Joy of Sex | Coach Hindenberg |
| 1984 | Street Hawk: The Movie | Anthony Corrido |
| 1984 | The Cowboy and the Ballerina | |
| 1983 | Mr. Mom | Larry |
| 1983 | To Be or Not to Be | Capt. Schultz |
| 1983 | September Gun | Jack Brian |
| 1982 | Cheers | Phillip Semenko |
| 1982 | National Lampoon's Movie Madness | Samuel Starkman ("Municipalians") |
| 1982 | Money on the Side | Sergeant Stampone |
| 1982 | Pilgrim, Farewell | Paul |
| 1981 | The Postman Always Rings Twice | The Salesman |
| 1981 | The Legend of the Lone Ranger | Maj. Bartholomew 'Butch' Cavendish |
| 1981 | Best of the West | The Calico Kid |
| 1980 | Schizoid | Gilbert |
| 1980 | The Black Marble | Arnold's Collector |
| 1980 | Semi-Tough | |
| 1979 | The Onion Field | Jailhouse Lawyer |
| 1979 | The Lady in Red | Frognose |
| 1979 | Butch and Sundance: The Early Days | Bill Carver |
| 1979 | The Fantastic Seven | Skip Hartman |
| 1978 | Taxi | Reverend Jim Ignatowski |
| 1978 | Taxi | Reverend Jim 'Iggy' Ignatowski |
| 1978 | Goin' South | Towfield |
| 1978 | The Word | Hans Bogardus |
| 1978 | Lacy and the Mississippi Queen | Jennings |
| 1977 | Un autre homme, une autre chance | Jesse James (uncredited) |
| 1977 | Three Warriors | |
| 1975 | One Flew Over the Cuckoo's Nest | Max Taber |
| 1975 | Saturday Night Live | Self - Cameo (uncredited) |
| 1975 | Barney Miller | Arnold Scully |
| 1975 | Barney Miller | Vincent Carew |
| 1956 | Tony Awards | Self - Performer (uncredited) |
