film
Absolutely Anything | 2015 | Dennis the Dog (voice)
Night at the Museum: Secret of the Tomb | 2014 | Theordore Roosevelt
Merry Friggin' Christmas | 2014 | Mitch
The Angriest Man in Brooklyn | 2014 | Henry Altman
Boulevard | 2014 | Nolan Mack
The Zero Theorem | 2013 | Church of Batman the Redeemer Billboard Spokesman
The Face of Love | 2013 | Roger
The Butler | 2013 | Dwight D. Eisenhower
The Big Wedding | 2013 | Father Monighan
Stage Left: A Story of Theater in the Bay Area | 2011 | Himself (documentary)
Happy Feet Two | 2011 | Ramon/Lovelace (voice)
Old Dogs | 2009 | Dan Rayburn
Night at the Museum: Battle of the Smithsonian | 2009 | Theodore Roosevelt
World's Greatest Dad | 2009 | Lance Clayton
Shrink | 2009 | Jack Holden
August Rush | 2007 | Maxwell 'Wizard' Wallace
License to Wed | 2007 | Reverend Frank
The Night Listener | 2006 | Gabriel Noone
RV | 2006 | Bob Munro
Everyone's Hero | 2006 | Napoleon Cross (voice)
Happy Feet | 2006 | Ramon/Lovelace (voice)
Night at the Museum | 2006 | Theordore Roosevelt
Man of the Year | 2006 | Tom Dobbs
The Aristocrats | 2005 | Himself
Robots | 2005 | Fender (voice)
The Big White | 2005 | Paul Barnell
The Final Cut | 2004 | Alan W. Hakman
House of D | 2004 | Pappass
Noel | 2004 | Charlie Boyd
One Hour Photo | 2002 | Seymour 'Sy' Parrish
Death to Smoochy | 2002 | 'Rainbow' Randolph Smiley
Insomnia | 2002 | Walter Finch
The Rutles 2: Can't Buy Me Lunch | 2002 | Hans Hänkie
A.I. Artificial Intelligence | 2001 | Dr. Know (voice)
Get Bruce | 1999 | Himself
Jakob the Liar | 1999 | Jakob Heym/Narrator
Bicenttennial Man | 1999 | Andrew Martin
What Dreams May Come | 1998 | Chris Nielsen
Junket Whore | 1998 | Himself
Patch Adams | 1998 | Hunter 'Patch' Adams
Fathers' Day | 1997 | Dale Putley
Deconstructing Harry | 1997 | Mel
Flubber | 1997 | Professor Philip Brainard
Good Will Hunting | 1997 | Sean Maguire
The Birdcage | 1996 | Armand Goldman
Jack | 1996 | Jack Powell
The Secret Agent | 1996 | The Professor
Hamlet | 1996 | Osric
Aladdin and the King of Thieves | 1996 | Genie (voice)
Nine Months | 1995 | Dr. Kosevich
To Wong Foo, Thanks for Everthing! Julie Newmar | 1995 | John Jacob Jingleheimer Schmidt
Jumanji | 1995 | Alan Parrish
In Search of Dr. Seuss | 1994 | Father
Being Human | 1994 | Hector
Mrs. Doubtfire | 1993 | Daniel Hillard/Euphegenia Doubtfire
Shakes the Clown | 1992 | Mime Class Instructor
FernGully: The Last Rainforest | 1992 | Batty Koda (voice)
The Timekeeper | 1992 | The Timekeeper (voice)
Aladdin | 1992 | Genie (voice)
Toys | 1992 | Leslie Zevo
Rabbit Ears: The Fool and the Flying Ship | 1991 | Narrator (voice)
Hook | 1991 | Peter Banning/Peter Pan
The Fisher King | 1991 | Henry 'Parry' Sagan
Dead Again | 1991 | Doctor Cozy Carlisle
The Earth Day Special | 1990 | Everyman
Awakenings | 1990 | Dr. Malcolm Sayer
Cadillac Man | 1990 | Joey O'Brien
I'm from Hollywood | 1989 | Himself
Dead Poets Society | 1989 | John Keating
Back to Neverland | 1989 | Himself (part of The Magic of Disney Animation attraction at Disney Resort)
Rabbit Ears: Pecos Bill | 1988 | Narrator (voice)
Portrait of a White Marriage | 1988 | Air Conditioning Salesman
The Adventures of Baron Munchausen | 1988 | King of the Moon
Good Morning, Vietnam | 1987 | Adrian Cronauer
A Night at the Met | 1986 | Robin Williams
The Best of Times | 1986 | Jack Dundee
Club Paradise | 1986 | Jack Moniker
Seize the Day | 1986 | Tommy Wilhelm
Moscow on the Hudson | 1984 | Vladimir Ivanov
The Survivors | 1983 | Donald Quinelle
The World According to Garp | 1982 | T.S. Garp
Popeye | 1980 | Popeye
Can I Do It 'Till I Need Glasses | 1977 | Lawyer, Man with Tooth Ache
television
The Crazy Ones | 2013-2014 | Simon Roberts | 22 epsiodes
Louie | 2012 | Robin | 'Barney/Never'
Wilfred | 2012 | Dr Eddy/Himself | 'Progress'
SongeBob SquarePants | 2009 | Himself | 'Truth or Square'
Law & Order: Special Victimns Unit | 2008 | Merritt Rook | 'Authority'
Life with Bonnie | 2003 | Kevin Powalski | 'Psychic'
Freedom: A History of Us | 2003 | Josiah Quincy, Ulysses S. Grant, Missouri farmer, Wilbur Wright, Orville Wright | 4 episodes
Whose Line Is It Anyway? | 2000 | Himself | season 3, episode 9
L.A. Doctors | 1999 | Hugo Kinsley | 'Just Duet'
One Saturday Morning | 1998 | Genie | 2 episodes
Friends | 1997 | Tomas | 'The One with the Ultimate Fighting Champion'
The Larry Sanders Show | 1992-1994 | Himself | 2 episodes
Homicide: Life on the Streets | 1994 | Robert Ellison | 'Bop Gun'
A Wish for Wings That Work | 1991 | The Kiwi (voice)
Big Bird's Birthday Celebration | 1991 | Himself | Sesame Street special
Sesame Street | 1990-2012 | Himself | 6 episodes
Dear America: Letters Home from Vietnam | 1987 | Baby-san (voice) | documentary
Pryor's Place | 1984 | Gaby | 'Sax Education'
SCTV Network | 1982 | various | 'Jane Eyrehead'
Faerie Tale Theatre | 1982 | Frog/Prince Robin | 'Tale of the Frog Prince'
E.T. and Friends: Magical Movie Visitors | 1982 | host, various | TV special
Out of the Blue | 1979 | Mork | 'Random's Arrival'
Happy Days | 1979 | Mork | 'Mork Returns'
Mork & Mindy | 1978-1982 | Mork | 92 episodes
America 2-Night | 1978 | Jason Shine | 2 episodes
Happy Days | 1978 | Mork | 'My Favorite Orkan'
Eight is Enough | 1977 | 'The Return of Auntie V'
Laugh-In | 1977
The Richard Pryor Show | 1977 | various | writer, 2 episodes
video games
Disney's Math Quest: Aladdin | 1998 | Genie (voice)
audio recordings
Weapons of Self Destruction | 2010 | spoken word recording
Robin Willians: Live on Broadway | 2002 | live performance
A Night at the Met | 1986 | live performance
Throbbing Python of Love | 1983 | spoken word recording
Reality... What A Concept | 1979 | spoken word recording
video recordings
Weapons of Self Destruction | 2010
Robin Williams: Inside the Acotrs Studio | 2008
Robin Williams: Live on Broadway | 2002
source: wikipedia