James B. Sikking, Actor Best Known for ‘Hill Street Blues,’ Dies at 90

James B. Sikking, an actor who specialized in comically and threateningly stern men, died on Saturday at his home in Los Angeles. He was 90.

The cause was complications of dementia, a spokeswoman, Cynthia Snyder, said in a statement.

Mr. Sikking combined a soldier’s leanness and square jaw with a gentleman’s horn-rimmed spectacles and neatly combed hair. As a Federal Bureau of Investigation director involved in high-level power players in the 1993 movie “The Pelican Brief,” he looked the part.

“I have that professional, intelligent look in my eye that hires me as doctors, lawyers, professional people,” he told The New York Times in 1988.

Among hundreds of roles on television, Mr. Sikking was best known for playing Lt. Howard Hunter on the police drama “Hill Street Blues” (1981-87). The show won 26 Emmys, a record for a drama until “The West Wing,” which ran from 1999 to 2006, reached the same total. The show “paved the way for today’s golden era of TV drama,” The Los Angeles Times wrote in 2014, a claim that many other commentators have made as well.

Mr. Sikking’s character, who appeared in every episode, was a pipe-smoking disciplinarian and weapons expert who, when alone at home, might whisper lovingly to a puppy.

He based the character’s persona and even dress on a drill instructor he had during a stint in the Army. “He was so ‘army’ that it was maddening,” Mr. Sikking told the entertainment and lifestyle publication Parade in 2014. “And he had just gotten his second lieutenant bars and he worked our butts off and he was totally unbending.”