His former costarNeil Patrick Harrispaid tribute to the late actor in a Monday social mediapost.

“A true professional.

It was an absolute honor to be his son.

James B. Sikking arrives to the show “Traces” Opening Night at The Ricardo Montalban Theatre on January 14, 2011 in Hollywood, California

James Sikking.Beck Starr/FilmMagic

My condolences to his actual family for their loss.”

Beck Starr/FilmMagic

Born March 5, 1934, the actor was named James Barrie Sikking after the renownedPeter Panauthor.

In 1981, he became a series regular onHill Street Bluesas the no-nonsense Vietnam War veteran Howard Hunter.

James Sikking as Dr. David Howser, Neil Patrick Harris as Doogie Howser and Belinda Montgomery as Katherine Howser.,

James Sikking as Dr. David Howser, Neil Patrick Harris as Doogie Howser and Belinda Montgomery as Katherine Howser in ‘Doogie Howser M.D.'.ABC/Getty

Sikking received an Emmy nomination for his performance in 1984.

So when I started to play Howard, I picked out the way he should be dressed.

It had to be a very military look.

Two years after the drama concluded, Sikking reunited withHill Street Bluescreator Steven Bochco forDoogie Howser, M.D.

He also appeared in the 1993 legal drama,The Pelican Brief.

Sikking is survived by his wife, two children, and four grandchildren.