(written from a Production point of view)
Although he began his acting career performing on the stage and has made several television appearances, his most extensive work has been in films. Perhaps his best known film roles are those of "Colonel Stuart" in 1990's Die Hard 2 (which featured his DS9 co-star Colm Meaney as the Irish Air pilot whose plane is crashed by Sadler's villainous Colonel Stuart and starred TNG guest star Robert Costanzo) and "Heywood" in 1994's The Shawshank Redemption. Among his co-stars in the latter film were fellow Star Trek alumni Bill Bolender, Clancy Brown, Jude Ciccolella, Bob Gunton, and Mark Rolston.
Sadler is also known for his role as the "Grim Reaper" in 1991's Bill & Ted's Bogus Journey, for which he won a Saturn Award from the Academy of Science Fiction, Fantasy & Horror Films. That film co-starred Roy Brocksmith, whom Sadler had previously co-starred with in the first episode of Tales from the Crypt (which also featured Patti Yasutake). Sadler would go on to play a different Grim Reaper in the Tales from the Crypt episode "The Assassin", co-starring Jonathan Banks and Marshall Teague.
Sadler's many other film credits include Trespass (1992, with Tommy "Tiny" Lister, Jr.), Tales from the Crypt Presents: Demon Knight (1995, with Dick Miller, Brenda Bakke, John Schuck, Tim de Zarn, and John Larroquette), and The Green Mile (1999, with James Cromwell and Paula Malcomson). He was also a star on the science fiction TV series Roswell, for which Ronald D. Moore became a chief writer, Jonathan Frakes was an executive producer and frequent director, and which also guest-starred Frakes as himself in two episodes, one of which also starred John Billingsley in a scene in which the main character auditions for a part on Star Trek: Enterprise.
He later starred in the series Wonderfalls, which ran for only one season in 2004, and Traveler, which again lasted for one summer season in 2007. The latter series also starred Steven Culp and Neal McDonough. He also had a recurring role on the HBO series The Pacific, which also features Conor O'Farrell. He also appeared in Alex Kurtzman's and Roberto Orci's remake of Hawaii Five-O as John McGarrett, Steve McGarrett's father and the former Honolulu PD training officer/partner of Daniel Dae Kim's character Chin Ho Kelly.
Appearances as Sloan
Other Trek connections
Additional non-Trek film and television projects in which Sadler has appeared with fellow Star Trek performers include:
- The Equalizer episode "Shades of Darkness" (1986) with Robert Lansing and Keith Szarabajka
- St. Elsewhere episode "The Abby Singer Show" (1988) with Ed Begley, Jr., Ronny Cox, France Nuyen, Alfre Woodard, and Jane Wyatt
- Murphy Brown episode "Off the Job Experience" (1989) with Alan Oppenheimer
- Poltergeist: The Legacy episode "The Fifth Sepulcher" (1996) with W. Morgan Sheppard
- JAG episode "Retrial" (2004) with Dean Stockwell and Ray Wise
- CSI: Crime Scene Investigation episode "Killer" (2006) with Susanna Thompson
- Numb3rs episode "Democracy" (2007) with Danica Erickson
- Fringe episode The Equation (2008), created by J.J. Abrams
- The Great Wallendas (1978) with Casey Biggs
- Charlie and the Great Balloon Chase (1981) with his "Inter Arma Enim Silent Leges" co-star Adrienne Barbeau
- Unconquered (1981) with Bob Gunton and Noble Willingham
- The Last to Go (1991) with Phillip Richard Allen, Terry O'Quinn, and Tim Ransom
- Tagget (1991) with Tim De Zarn, Glenn Morshower and Leon Russom
- Jack Reed: Badge of Honor (1993) with Bruce Bolender, Bruce French, Alice Krige, Neal McDonough
- The Omen (1995) with Norman Lloyd
- Witness Protection (1999) with Jim Metzler and Leon Russom
- Off Beat (1986) with Anthony Zerbe and Mike Starr
- Project X (1987) with Shelly Desai, Robin Gammell, Dick Miller, and Daniel Roebuck
- K-9 (1989) with Jeff Allin, Daniel Davis, and Sherman Howard
- The Hot Spot (1990) with Virginia Madsen and Leon Rippy
- Hard to Kill (1990) with Branscombe Richmond
- Freaked (1993) with Lee Arenberg, Derek McGrath, and Don Stark
- Tales from the Crypt Presents: Bordello of Blood (1996) with Whoopi Goldberg and Chris Sarandon
- Ambushed (1998) with Virginia Madsen
- Stealth Fighter (1999) with Tommy "Tiny" Lister, Jr.
- The Battle of Shaker Heights (2003) with France Nuyen and Ray Wise
- Purple Heart (2005) with Ed Lauter
- Confess (2005) with Josh Pais