James Sikking, who starred in shows like "Doogie Howser, M.D." and "Hill Street Blues" has died at age 90.

In a statement Sunday evening, Sikking's publicist Cynthia Snyder said the actor died of complications from dementia.

Snyder shared with Fox News Digital, "In a remarkable career, Sikking’s wonderfully exciting face gave us drama, comedy, tragedy and hilarious farse. His career spanned over six decades in television, film and on stage."

She added, "His talent, integrity and imagination intrigued and delighted audiences."

'HILL STREET BLUES' STAR BARBARA BOSSON DEAD AT 83

On "Doogie Howser, M.D.," Sikking played Dr. David Howser, father to the title character of the series, played by Neil Patrick Harris.

Before that, he starred as Lt. Howard Hunter on "Hill Street Blues," a clean-cut Vietnam War veteran who headed the Emergency Action Team of the Metropolitan Police Department.

Sikiking based his character's uptight and quirky nature on a drill instructor he'd had at basic training when military service cut through his time at the University of California, Los Angeles, from which he graduated in 1959.

"The drill instructor looked like he had steel for hair and his uniform had so much starch in it, you knew it would sit in the corner when he took it off in the barracks," he told The Fresno Bee in 2014.

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

He earned an Emmy nomination for outstanding supporting actor in a drama in 1984.

Apart from his work in "Hill Street Blues" and "Doogie Howser, M.D.," Sikking also appeared in "Star Trek III: The Search for Spock."

In his later career, he had guest spots on shows like "Curb Your Enthusiasm" and "The Closer," as well as parts in films like "Fever Pitch" and "Made of Honor."

LIKE WHAT YOU’RE READING? CLICK HERE FOR MORE ENTERTAINMENT NEWS

Sikking was born the youngest of five in 1934 in Los Angeles. Some of his early work includes an uncredited part in Roger Corman's "Five Guns West" and a small part in an episode of "Perry Mason."

He also had guest starring roles on several series like "Mission: Impossible," "M*A*S*H," "The F.B.I.," "The Rockford Files," "Hawaii Five-O" and "Charlie's Angels" before landing his role on "Hill Street Blues."

Sikking married Florine Caplan, with whom he had two children and four grandchildren.

The Associated Press contributed to this report.

JESSE WATTERS: We don't know if the alleged assassin acted alone or if he was a part of a conspiracy. The FBI is telling us he was a lone actor, but we don't trust the FBI. We don't trust the media. All Americans should be skeptical about what they hear. Reagan's wannabe assassin was a lone wolf. JFK's assassin wasn't. He had help, and there was a cover-up. So our job is to be curious. This is the most serious assassination attempt in 40 years. How can a man climb a ladder onto a roof, mount a rifle, and unload eight rounds at a former president from 130 yards? We'll have a full report on the shooter, Thomas Matthew Crooks, coming up. The shots came from the roof of American Glass Research, the company that we'll be investigating. Did the shooter case the building beforehand? 

WHO WAS THOMAS MATTHEW CROOKS? WHAT WE KNOW ABOUT TRUMP'S ATTEMPTED ASSASSIN

Why didn't the Secret Service, when they surveyed the site of the rally, account for this building? Why weren't there counter-snipers on that roof? The Associated Press says a local police officer saw Crooks climb the roof, but when he confronted him, Crooks pointed his rifle at him and the officer retreated. And then Crooks opened fire on 45. The FBI is denying that report, which is weird because the FBI never comments on active investigations. Many other people noticed the shooter on the roof. 

Why did it take eight rounds to ring out before somebody returned fire? Sources tell "Primetime" that the counter-sniper team that neutralized Crooks were Secret Service sharpshooters, but the Washington Post reports that the counter-snipers were local cops. Now, if that's true, why is the Secret Service relying so heavily on locals? 

And why did the counter-snipers who had their rifles trained on this assassin not shoot first?