Filmography72 titles
| Year | Title | Character | Age at release |
|---|---|---|---|
| 2024 | The Six Triple EightMovie | Franklin Delano Roosevelt | 84 |
| 2023 | Liv Ullmann: A Road Less TravelledSeries | Self | 83 |
| 2022 | The DropoutSeries | George Shultz | 82 |
| 2020 | Gatsby in Connecticut: The Untold StoryMovie | Self | 80 |
| 2018 | On the Basis of SexMovie | Erwin Griswold | 78 |
| 2018 | The Mayo ClinicMovie | Charlie Mayo (voice) | 78 |
| 2017 | GodlessSeries | Marshall John Cook | 77 |
| 2016 | Miss SloaneMovie | George Dupont | 76 |
| 2016 | AnesthesiaMovie | Prof. Walter Zarrow | 76 |
| 2015 | The Late Show with Stephen ColbertSeries | Self - Guest | 75 |
| 2015 | Grace and FrankieSeries | Sol Bergstein | 75 |
| 2012 | The NewsroomSeries | Charlie Skinner | 72 |
| 2011 | ProhibitionSeries | Reader (voice) | 71 |
| 2010 | The Rally to Restore Sanity and/or FearMovie | Self | 70 |
| 2006 | The Best of The Tony Awards: The PlaysMovie | John Honeyman (segment "A Walk in the Woods") | 66 |
| 2005 | The Colbert ReportSeries | Self (uncredited) | 65 |
| 2005 | Law & Order: Trial by JurySeries | Jack McCoy | 65 |
| 2003 | Le DivorceMovie | Chester Walker | 63 |
| 2003 | The CommissionMovie | J. Lee Rankin | 63 |
| 2000 | A House DividedMovie | David Dickson | 60 |
| 1999 | Law & Order: Special Victims UnitSeries | Jack McCoy | 59 |
| 1999 | Family GuySeries | Bruce Kaplan (voice) | 59 |
| 1999 | The Unfinished JourneyMovie | Narrator (voice) | 59 |
| 1998 | ExiledMovie | Jack McCoy | 58 |
| 1997 | The ViewSeries | Self | 57 |
| 1997 | Shadow ConspiracyMovie | The President | 57 |
| 1997 | Thomas JeffersonSeries | Thomas Jefferson (voice) | 57 |
| 1995 | NixonMovie | Richard Helms | 55 |
| 1995 | The Journey of August KingMovie | Mooney Wright | 55 |
| 1994 | Serial MomMovie | Eugene Sutphin | 54 |
| 1993 | Homicide: Life on the StreetSeries | Jack McCoy | 53 |
| 1992 | HBO First LookSeries | — | 52 |
| 1992 | Earth and the American DreamMovie | Reader (voice) | 52 |
| 1991 | The Man in the MoonMovie | Matthew Trant | 51 |
| 1990 | Law & OrderSeries | Jack McCoy | 50 |
| 1990 | The Civil WarSeries | Abraham Lincoln | 50 |
| 1990 | Night of 100 Stars IIIMovie | Self | 50 |
| 1989 | Tales from the CryptSeries | G.G. Devoe (segment "As Ye Sow") | 49 |
| 1989 | Lantern HillMovie | Andrew Stuart | 49 |
| 1989 | Crimes and MisdemeanorsMovie | Ben | 49 |
| 1988 | Terrorist on Trial: The United States vs. Salim AjamiMovie | Jim Delmore | 48 |
| 1988 | LincolnSeries | Abraham Lincoln | 48 |
| 1987 | The Room UpstairsMovie | Travis Coles | 47 |
| 1987 | Devil's ParadiseMovie | Jones | 47 |
| 1986 | Hannah and Her SistersMovie | David (uncredited) | 46 |
| 1986 | Just Between FriendsMovie | Harry Crandall | 46 |
| 1986 | The Fifth MissileMovie | Capt. Allard Renslow | 46 |
| 1986 | Flagrant désirMovie | Inspecteur Gerry Morrison | 46 |
| 1985 | Amazing StoriesSeries | Jordan Manmouth | 45 |
| 1985 | Finnegan Begin AgainMovie | Paul Broadbent | 45 |
| 1984 | Jeopardy!Series | Self | 44 |
| 1984 | The Killing FieldsMovie | Sydney Schanberg | 44 |
| 1982 | Q.E.D.Series | Professor Quentin Everett Deverill | 42 |
| 1982 | American PlayhouseSeries | Robert Oppenheimer | 42 |
| 1980 | Heaven's GateMovie | Frank Canton | 40 |
| 1980 | OppenheimerSeries | Robert Oppenheimer | 40 |
| 1980 | Friendly FireMovie | C.D.B. Bryan | 40 |
| 1978 | InteriorsMovie | Mike | 38 |
| 1977 | Capricorn OneMovie | Lt. Col. Peter Willis | 37 |
| 1975 | Saturday Night LiveSeries | Self (uncredited) | 35 |
| 1975 | Rancho DeluxeMovie | Cecil Colson | 35 |
| 1975 | People's Choice AwardsSeries | Self - Presenter | 35 |
| 1975 | Journey into FearMovie | Mr. Graham | 35 |
| 1974 | The Great GatsbyMovie | Nick Carraway | 34 |
| 1974 | Reflections of MurderMovie | Michael Elliott | 34 |
| 1973 | Much Ado About NothingMovie | Benedick | 33 |
| 1972 | SavagesMovie | James, the Limping Man | 32 |
| 1971 | Who Killed Mary Whats'ername?Movie | Alex Monte | 31 |
| 1971 | Film '72Series | Self | 31 |
| 1967 | FitzwillyMovie | Oliver | 27 |
| 1961 | Dr. KildareSeries | Mark | 21 |
| 1951 | Hallmark Hall of FameSeries | Travis Coles | 11 |