Brown began his acting career in the early 1980s with an appearance in The Dukes of Hazzard. He is mostly recognizable for his role as the protagonist's friend in The Adventures of Buckaroo Banzai Across the 8th Dimension (1984), The Kurgan in Highlander (1986), prison guard Byron Hadley in The Shawshank Redemption (1994), a drill instructor in Starship Troopers (1997) and the preacher Meacham in Cowboys & Aliens (2011).
Having a deep and resonant voice, he also works as a voice actor for both animation and video games, including Mortal Kombat (1995), Gargoyles (1995–1996), SpongeBob SquarePants (1999–present) and Avatar: The Last Airbender (2005–2008; a show which featured heavy involvement from Dave Filoni and Giancarlo Volpe). He also voiced Lex Luthor in the DC Animated Universe's Superman: The Animated Series (1996–2000), Justice League (2001–2004) and Justice League Unlimited (2004–2006).
Clancy Brown provided the voice of the Mandalorian bounty hunter Montross in Star Wars: Bounty Hunter, the Nightbrother turned Sith Lord Savage Opress in The Clone Wars, and Imperial Governor turned Rebel Alliance member Ryder Azadi for Star Wars Rebels. He reprised the role of Azadi in live-action in the Ahsoka television series. He also portrayed the Devaronian Burg in the Disney+ live-action TV series The Mandalorian.
- Star Wars: The Lightsaber Collection