Richard Riehle, a prolific character actor whose bushy mustache and knack for portraying beleaguered middlemen made him a favorite of Hollywood casting directors for decades, has died, his representatives said Monday.

He was 78. Riehle’s representatives said he died over the weekend but did not provide details about the cause.

Riehle was best known for his supporting role in Mike Judge’s corporate satire “Office Space” as Tom Smykowski, an anxious product manager who rages against the prospect of getting laid off. (“I have people skills! I am good at dealing with people! Can’t you understand that?”).

He left an impression even with scant screen time, whether playing a racist quartermaster in “Glory,” a guard who allows Harrison Ford to flee in “The Fugitive,” a mob banker who gets cursed out by Joe Pesci in Martin Scorsese’s “Casino,” or a kindly auto mechanic who helps out Kristen Wiig in “Bridesmaids.”

Riehle’s hundreds of credits include scores of TV roles, such as Principal Ed Rooney on the short-lived sitcom “Ferris Bueller,” a gruff grandfather on “Grounded for Life” and a police officer on “The West Wing.” He most recently appeared as a prison warden on HBO’s dark comedy “Barry.”

“Beyond his immense talent, he will be remembered for his genuine goodness, boundless kindness, and unwavering generosity, particularly toward emerging actors and filmmakers, whom he encouraged and supported at every opportunity,” his talent agency and management company said in a statement.

“Grounded for Life” star Donal Logue paid tribute to Riehle on Facebook, describing his co-star as “an amazing human being” and a “consummate professional.”

“He was an actor’s actor — humble, kind, and incredible at his craft,” Logue wrote. “I had to apologize to him after his final network audition for ‘Grounded’ because he made me laugh so hard, I broke character and fell to the floor.”

Riehle made his screen acting debut as an unnamed bartender in the 1977 road-trip movie “Joyride,” the first of more than 400 credits across film and television.

Richard Mathias Riehle was born on May 12, 1948, in Menomonee Falls, Wisconsin. He attended the University of Notre Dame, where he joined the campus theatrical group and grew fond of stage acting.

“I always wanted the role that would bring something out of me, force me to find something extra,” Riehle told Notre Dame Magazine for the winter 2011-2012 issue. “The lead isn’t always the best part in a play or a movie.”