James Sikking of “Hill Street Blues” has died at 90. His publicist Cynthia Snyder said in a statement Sunday evening that Sikking died of complications from dementia.

James Sikking, who starred as a hardened police lieutenant on “Hill Street Blues” and as the titular character’s kindhearted dad on “Doogie Howser, M.D.,” has died at 90.

Sikking died of complications from dementia, his publicist Cynthia Snyder said in a statement Sunday evening.

Born the youngest of five children on March 5, 1934 in Los Angeles, his early acting ventures included an uncredited part in Roger Corman’s “Five Guns West” and a bit role in an episode of “Perry Mason.” He also secured guest spots in a litany of popular 1970s television series, from the action-packed “Mission: Impossible,” “M.A.S.H.” “The F.B.I.,” “The Rockford Files,” “Hawaii Five-O” and “Charlie’s Angels” to “Eight is Enough” and “Little House on the Prairie.”

“Hill Street Blues” would debut in 1981, a fresh take on the traditional police procedural. Sikking played Lt. Howard Hunter, a clean-cut Vietnam War veteran who headed the Emergency Action Team of the Metropolitan Police Department in a never-named city.