Actor Nicky Katt, who portrayed tough characters and wild cards in movies like “Dazed and Confused” and “Boiler Room” and on television programs like “Boston Public,” has away. His age was 54.

John Sloss, his attorney, confirmed his death but gave no more information.

Working with well-known filmmakers like Richard Linklater, Christopher Nolan, and Steven Soderbergh, Mr. Katt started his career as a child actor before transitioning into character acting, specializing in ruthless villains.

Mr. Katt was frequently portrayed as a forceful, erratic individual whose qualities, if any, were not readily apparent.

He plays a nerdy high school taunter in “Dazed and Confused,” gritting his teeth and beating up a fellow student. As Clint Bruno, Mr. Katt boastfully declared, “I came here to do two things, man: kick some ass and drink some beer.” “It appears that our beer supply is almost depleted.”

Mr. Katt played Harry Senate, a flamboyant rule-breaker and geology teacher who uses a handgun to draw attention to his class and disarms a kid who was threatening another teacher with a gun in the television series “Boston Public” (Fox, 2000–2004), which was set in an urban high school.

Mr. Soderbergh called Mr. Katt’s performances “dangerously out of control” yet “rigorously studied” in an interview with The Los Angeles Times in 2002.

“There is no fear at all,” Mr. Soderbergh remarked. “No concept is too ridiculous. He will attempt anything.

In May 1970, Nicky Katt was born in South Dakota. As a preteen, he had appearances on a number of television programs, such as “Fantasy Island” and “ChiPs.”

Full details regarding his surviving and family were not immediately accessible.

Mr. Katt told The Los Angeles Times that he thought most performers were either dissatisfied or desperate. Mr. Katt accumulated a vast collection of quotations and tales from renowned historical personalities to help him deal with the whims of the profession.

He gave the following bit of advice: “Never name-drop.” “I heard that from De Niro.”