Robert Trebor, who portrayed the serial killer known as the Son of Sam in a CBS telefilm and the scheming merchant Salmoneus on Hercules: The Legendary Journeys and its sister series, Xena: Warrior Princess, has died. He was 71.

Trebor died March 11 at Los Angeles Medical Center of sepsis, his wife, Deirdre Hennings, told The Hollywood Reporter. He was diagnosed with leukemia in 2012 and had a stem-cell transplant a year later, she said.

On the big screen, the clever character actor worked in films including John Frankenheimer’s 52 Pickup (1986), Susan Seidelman’s Making Mr. Right (1987), Oliver Stone’s Talk Radio (1988) and the Coen brothers’ Hail, Caesar (2016), for which he played a movie producer in his final onscreen role.

In his breakout year of 1985, Trebor appeared as a reporter in Woody Allen’s The Purple Rose of Cairo, as a copy boy in Bob Clark’s Turk 182 and as the...