| Year | Title | Role | Notes |
|---|
| 1979 | B.J. and the Bear | Forman | television debut
Episode: "The Eyes of Texas" |
| 1980 | Rage! | Man #C | Television Movie |
| 1981 | The Incredible Hulk | Mechanic | Episode: "Fast Lane" |
| 1982 | Fame | Driver Cop | Episode: "Tomorrow's Farewell" |
| 1982 | The Fall Guy | Bleeker | Episode: "A Piece of Cake" |
| Pete | Episode: "No Way Out" |
| 1987 | Spenser: For Hire | Monroe | Episode: "My Enemy, My Friend" |
| Ken Green | Episode: "I Confess" |
| 1987 | Leg Work | Clauson | Episode: "The Art of Murder" |
| 1988 | Alone in the Neon Jungle | Alan Benson | Television Movie |
| 1988 | Miami Vice | Charles Hatch | Episode: "Hell Hath No Fury" |
| 1988 | Tattinger's | Mcintosh's Torpedo | Episode: "Pilot" |
| 1989 | A Man Called Hawk | Unknown | Episode: "The Master's Mirror" |
| 1990 | ABC Afterschool Specials | Unknown | Episode: "All That Glitters" |
| 1990 | Law & Order | Freddo Parisi | Episode: "Poison Ivy" |
| 1991 | Posing: Inspired by Three Real Stories | Jimmy Lanahan | Television Movie |
| 1992 | Quantum Leap | Admiral Spencer | Episode: "Running for Honor - June 11, 1964" |
| 1992 | Matlock | Sheriff Dewey | Episode: "The Outcast" |
| 1992 | Quicksand: No Escape | Detective Harris | credited as John Joseph Harris |
| 1992 | Street Justice | Unknown | Episode: "Eye Witness" |
| 1992 | Cheers | Mitch Ganzell | Episode: "Take Me Out of the Ball Game" |
| 1992 | Steel Justice | Lieutenant Bill Somes | Television Movie |
| 1992 | Lady Against the Odds | Lieutenant Donnelly | Television Movie |
| 1992 | Mario and the Mob | Unknown | Television Movie |
| 1992 | Citizen Cohn | Senator Charles Potter | Television Movie |
| 1992 | Flying Blind | Mr. Rickman | Episode: "Pilot" |
| 1993 | Frasier | Tim | Episode: "Miracle on Third or Fourth Street" credited as John J. Finn |
| 1994 | SeaQuest 2032 | Colonel Schrader | Episode: "Nothing But the Truth" |
| 1994-1995 | Chicago Hope | Dr. Trevor Filburn | 3 episodes; recurring role |
| 1995 | Truman | Bob Hannegan | Television Movie |
| 1995 | The Client | Waite Calhoun | Episode: "A Perfect World" |
| 1995 | Murderous Intent | Unknown | Television Movie |
| 1995 | Runaway One | Colonel Van Damme | Television Movie |
| 1995 | NYPD Blue | Jimmy "Socks" Matlow | Episode: "Dirty Socks" |
| 1996 | JAG | Major Klein | Episode: "Boot" |
| 1996 | Gone in the Night | Gerry Harbin | Television Movie |
| 1996 | Nash Bridges | FBI Special Agent Elliot Rose | Episode: "Aloha Bash" |
| 1996 | Crazy Horse | General George Crook | Television Movie |
| 1996-1997 | EZ Streets | Captain Geary | 11 episodes; recurring role |
| 1997 | Promised Land | Frank Boller | Episode: "The Getaway" |
| 1997 | Millennium | William Garry | Episode: "Covenant" |
| 1997 | Invasion | Airbase Colonel Brown (uncredited) | Miniseries |
| 1997 | Players | Lieutenant Mike Harper | Episode: "Rashocon" |
| 1997 | NYPD Blue | Lieutenant John Shanon | 2 episodes |
| 1997-1999 | The X-Files | Michael Kritschgau | 5 episodes; recurring role |
| 1998 | Brooklyn South | Officer Ray MacElwaine | 8 episodes; recurring role |
| 1999 | Strange World | FBI Special Agent Richard H. Hoffman | 2 episodes |
| 1999 | Atomic Train | Wally Phister | Miniseries; 2 episodes |
| 1999 | Seasons of Love | Gorm Schrader | 2 episodes |
| 1999-2003 | Dawson's Creek | Sheriff John Witter | 4 episodes; recurring role |
| 2000 | The Practice | Detective Henry Dokes | 2 episodes |
| 2000 | Deadlocked | Jack Fisque | Television Movie |
| 2000 | Rocket's Red Glare | Wyatt Claybourne | Television Movie |
| 2001 | Cover Me: Based on the True Life of an FBI Family | Nathan Martson | Episode: "The River" |
| 2001 | NYPD Blue | Jimmy McElroy | Episode: "Nariz a Nariz" |
| 2001 | Philly | Frank Maguire | Episode: "Light My Fire" |
| 2002 | Shadow Realm | Malone | Television Movie |
| 2002 | Thieves | George Lieser | Episode: "Home Is Where the Heist Is" |
| 2002 | Night Visions | Malone | Episode: "Patters/Voices" (segment: Voices) |
| 2002 | Without a Trace | Abner Harrington | Episode: "In Extremis" |
| 2003-2010 | Cold Case | John Stillman | series regular; 156 episodes/Director; 2 episodes
Episode: "Wednesday's Women" (2008)
Episode: "The Runaway Bunny" (2010) |
| 2011-2017 | NCIS | General (former Marine Commandant) Charles T. Ellison | 3 episodes |
| 2012 | Blue Bloods | David Cummings | Episode: "Leap of Faith" |
| 2012 | Suits | Lawrence Kemp | 2 episodes |
| 2012 | Homeland | Rex Henning | Episode: "The Clearing" |
| 2013 | Golden Boy | Ed McKenzie | Episode: "McKenzie on Fire" |
| 2014 | Believe | Mr. Tate | Episode: "Sinking" |
| 2014 | Madam Secretary | Allen Bollings | Episode: "Blame Canada" |
| 2014 | An Bronntanas | Sean Og | Miniseries, 5 episodes |
| 2014 | Wall Street | Ritter | Television Movie |
| 2015 | The Blacklist | Judge Richard Denner | 2 episodes |
| 2016 | Elementary | Neil Dannon | Episode: "Down Where the Dead Delight" |
| 2016 | The Good Wife | Oren Cleary | Episode: "Targets" |
| 2017 | Doubt | Don Wilson | Episode: "Pilot" |
| 2018-2020 | The Walking Dead | Earl Sutton [1] [2] [3] | 11 episodes |
| 2018 | The Enemy Within | Richard Bregman | Episode: "Pilot" |
| 2019 | The Loudest Voice | Jack Welch | Miniseries, 1 episode |
| 2019 | The Crown | Arthur "Bull" Hancock | Episode: "Coup" |
| 2021 | Arctic Circle | Gordon Merriman | Season 2, 6 episodes |
| 2024 | FBI: Most Wanted | Jackson Chase | Episode: "White Buffalo" |
