Filmography
| Year | Film | Role | Notes |
|---|---|---|---|
| 1965 | The Overfamiliar Subordinate | ||
| 1980 | F.D.R.: The Last Year (TV) | Thomas E. Dewey | |
| Phobia | Sgt Wheeler | ||
| 1983 | Hot Money | Parker | |
| Tell Me That You Love Me | David | ||
| Of Unknown Origin | James Hall | ||
| 1984 | Reno and the Doc (TV) | Reno | |
| Covergirl | Harrison | ||
| Falling in Love | Doctor | ||
| 1985 | The War Boy | Stephan Berecky | |
| The Cuckoo Bird (TV) | Harry | ||
| The Ray Bradbury Theater (Season 1, episode 1 Marionettes, Inc.) | Crane | ||
| Empire, Inc. (mini TV series) | Sir James Munroe | ||
| Love & Larceny (TV) | |||
| 1986 | Lost! | Jim | |
| Murder Sees the Light (TV) | The Evangelist | ||
| 1987 | And Then You Die | ||
| Loyalties | David Sutton | ||
| Radio Days | Radio Voice | voice only | |
| 1988 | The Murder of Mary Phagan (TV) | Luther Rosser | |
| The House on Carroll Street | Hackett | ||
| "Crocodile" Dundee II | Brannigan | ||
| Liberace: Behind the Music | |||
| The Twilight Zone Acts of Terror | Jack Simonson | ||
| Another Woman | |||
| 1989 | Love and Hate: The Story of Colin and Joanne Thatcher (TV) | Colin Thatcher | |
| Physical Evidence | Harry Norton | ||
| Dick Francis: Blood Sport | Harry Teller | ||
| 1990 | The Ray Bradbury Theater (Season 4, Episode 7, And the Moon Be Still as Bright) (TV) | Captain Wilder | |
| The Widowmaker (TV) | Atkinson | ||
| Twin Peaks (TV) | Windom Earle | ||
| Murder Times Seven (TV) | Nick Ruggieri | ||
| 1992 | Eli's Lesson | Uncle Yakub | |
| Dead Ahead: The Exxon Valdez Disaster (TV) | Sam Skinner | ||
| The Good Fight (TV) | Dick Chandler | ||
| 1993 | Woman on the Run: The Lawrencia Bembenek Story (TV) | Don Eisenberg | |
| Shattered Trust: The Shari Karney Story (TV) | Judge Norton | ||
| 1994 | Boozecan | Tim | |
| Death Wish V: The Face of Death | Lt. Mickey King | ||
| Kung Fu: The Legend Continues: episode Temple (TV) | Vance Cavanaugh | ||
| Timecop | Senator Utley | ||
| Legends of the Fall | Sheriff Tynert | ||
| 1995 | Hiroshima (TV) | President Harry S. Truman | |
| Kissinger and Nixon (TV) | James 'Scotty' Reston | ||
| The X Files - episode Revelations (TV) | Simon Gates |
- Portraits of a Killer (1996) as Jim Miller
- Habitat (1997) as Coach Marlowe
- Edison: The Wizard of Light (1998) (TV) as Thomas Edison
- Law & Order
- Disappeared (1998 TV Episode) as Ben O'Dell
- Thunder Point (1998) (TV) as Armstrong
- Thanks of a Grateful Nation (1998) (TV) as Sen. Shelby
- External Affairs (1999) as Michael Riordan
- Who Killed Atlanta's Children? (2000) (TV) as William Kunstler
- Dr. Watson in four Hallmark Sherlock Holmes television films:
- The Hound of the Baskervilles (2000) (TV)
- The Royal Scandal (2001) (TV)
- The Sign of Four (2001) (TV)
- The Case of the Whitechapel Vampire (2002) (TV)
- Witchblade (2000) (TV) as Joe Siri
- Haven (2001) (TV) as Harry Truman
- Focus (2001) as Father Crighton
- The Day Reagan Was Shot (2001) (TV) as James Baker
- Ice Bound: A Woman's Survival at the South Pole (2003) (TV) as Dr. Ben Murdoch
- Eloise at the Plaza (2003) (TV) as Sir Wilkes
- The Pentagon Papers (2003) (TV) as John McNaughon
- Eloise at Christmastime (2003) (TV) as Sir Wilkes
- Miracle (2004) as Doc Nagobads
- The Wild Guys (2004) as Andy
- The Day After Tomorrow (2004) as Vice President/President Raymond Becker
- H₂O (2004) (TV) as Randall Spear
- The Aviator (2004) as Dr. Hepburn
- Bailey's Billion$ (2005) as Mouse Delaney
- This Is Wonderland
- Episode #2.3 (2005) TV Episode
- Tilt
- The Aftermath (2005 TV Episode) as Seymour Henderson
- The Whale (2005 TV Episode) as Seymour Henderson
- Risk Tolerance (2005 TV Episode as Seymour Annisman
- The Game (2005 TV Episode) as Seymour Henderson
- Our Fathers (2005) (TV) as Bishop Murphy
- Four Brothers (2005) as Robert Bradford
- The Exorcism of Emily Rose (2005) (as Ken Welsh) as Dr. Mueller
- The Fog (2005) as Tom Malone
- ReGenesis
- Spare Parts (2004 TV Episode) as Dr. Shelby Sloane
- Baby Bomb (2004 TV Episode) as Dr. Shelby Sloane
- The Face of God (2005 TV Episode) as Dr. Shelby Sloane
- Category 7: The End of the World (2005) (mini TV Series) as Chief of Staff Alan Horst
- Smallville
- Lexmas (2005 TV Episode) as Drunk Santa
- The Snow Queen (2005) (TV) as King
- Above and Beyond (2005) (mini TV Series, in post-production) as Lord Beaverbrook
- Kit Kittredge: An American Girl (2008) as Uncle Hendrick
- Survival of the Dead (2009)
- Human Target (2010) as Belvilacqua
- Haven (2011) (episode "The Tides That Bind") as Cole Glendower
Read more about this topic: Kenneth Welsh