George Ames Plimpton (March 18, 1927 – September 25, 2003) was an American journalist, writer, literary editor, actor and occasional amateur sportsman. He is widely known for his sports writing and for helping to found The Paris Review, as well as his patrician demeanor and accent. Description above from the Wikipedia article George Plimpton, licensed under CC-BY-SA, full list of contributors on Wikipedia.
Good Will Hunting
As Psychologist
Little Man Tate
As Winston F. Buckner
Garbo Talks
As Self (uncredited)
Rio Lobo
As Fourth Gunman
Reds
As Horace Whigham
Volunteers
As Lawrence Bourne Jr.
Just Visiting
As Dr. Brady
A Fool and His Money
As Gott
Plimpton! Starring George Plimpton as Himself
As Himself (archive footage)
The Donner Party
As voice
The Capote Tapes
As Self (voice) (archive footage)
Beyond the Law
As Mayor
Sam the Man
As Self
Playboy's 25th Anniversary Celebration
As Narrator
Nixon
As President's Lawyer
Coney Island
As (voice)
If Ever I See You Again
As Lawrence
The Detective
As Reporter
The Private Files of J. Edgar Hoover
As Quentin Reynolds
L.A. Story
As Straight Weatherman
The Queen
As Self
When We Were Kings
As Self
Lawrence of Arabia
As Bedouin (uncredited)
Drunk Stoned Brilliant Dead: The Story of the National Lampoon
As Self / Actor (archive footage)
Factory Girl
As Himself
Good Morning, Mr. Orwell
As Self
Soul Power
As Self (archive footage)
Just Cause
As Elder Phillips
Uncensored Channels: TV Around The World With George Plimpton
As Himself (Host)
EDtv
As Panel Member
Bullet In The Brain
As Narrator
The Last Days of Disco
As Clubgoer
Plimpton! Shoot-Out at Rio Lobo
As Narrator
The Simpsons
As George Plimpton (voice)
The Single Guy
As George Plimpton
E! True Hollywood Story
Deadline
Wings
As Dr. Greyson
Central Park West
The Equalizer
As Clinton Brandauer
Just Shoot Me!
As George Plimpton
ER
As John Carter Sr.
Saturday Night Live
As Self - Cameo (uncredited)
American Experience
As Self (voice)
The Civil War
As George Templeton Strong
Baseball
As Self
The West
As Self (voice)
A Nero Wolfe Mystery
As Winterhoff
The Dick Cavett Show
As Self - Guest
Kraft Music Hall
As Self
The Tonight Show Starring Johnny Carson
As Self