Movies
* The Silence of the Lambs (1991): He played the role of Paul Krendler, the ambitious FBI agent.
* The Score (2001): He starred as Nick Wells, the right-hand man of a notorious jewel thief.
* Murder by Numbers (2002): He portrayed the detective investigating a high school murder.
* Star Trek: Nemesis (2002): He played the role of the Romulan admiral, Donatra.
* The Day the Earth Stood Still (2008): He appeared as a military general.
* The Taking of Pelham 1 2 3 (2009): He starred as the subway dispatcher.
* The Lovely Bones (2009): He played the role of the detective investigating a murder.
* A Most Violent Year (2014): He had a supporting role as a mob boss.
* The Finest Hours (2016): He played the role of the Coast Guard captain.
* The Irishman (2019): He had a supporting role as a corrupt union leader.
Television
* Miami Vice (1985-1989): He appeared in several episodes as various characters.
* Law & Order (1990-2010): He appeared in various roles throughout the series.
* The Wire (2002-2008): He portrayed the corrupt lawyer, Frank Sobotka.
* CSI: Crime Scene Investigation (2000-2015): He had recurring roles in multiple seasons.
* Justified (2010-2015): He played the role of the powerful, eccentric lawyer, Art Mullen.
* Ray Donovan (2013-2020): He had a major recurring role as the powerful, corrupt lawyer, Ezra Stern.
* Bosch (2014-2021): He played the role of Harry Bosch's former boss and mentor, Irvin Irving.
* The Handmaid's Tale (2017-present): He had a recurring role as a commander in Gilead.
* Mindhunter (2017-2019): He played the role of the FBI psychologist, Dr. Wendy Carr.
* The Alienist (2018): He had a recurring role as the wealthy businessman, Theodore Roosevelt.
This is just a small selection of his extensive work. Leland Orser has also appeared in numerous other films, TV shows, and even stage productions. He is a highly respected and versatile actor known for his ability to bring depth and authenticity to every role he takes on.