The actor died Thursday at a hospital in London following a long term illness ... according to a family member. We're told David was surrounded by his family when he passed.

David suffered from a number of health issues in his life ... most notably chronic obstructive pulmonary disease. He blames COPD on a half-century of smoking three packs of cigarettes daily.

His wife Helen Snell said the "beloved husband, father, grandfather and brother died yesterday after a valiant battle for life in the loving company of family. He shared many extraordinary gifts in the world as actor, singer, storyteller, creative artist and dear friend."

She added, "His smile, laughter and passion for life will be remembered by the many whose lives he has touched."

David became a pop icon in the 1970s in his starring role as Hutch, the blonde-haired, blue-eyed detective opposite Paul Michael Glaser as Detective Dave Starsky. He appeared in all 92 episodes from 1975-79, covering four seasons on TV, and also directed a few episodes.

After "Starsky and Hutch," David landed roles in the 1979 TV miniseries "Salem's Lot" and the  1980 TV movie "Homeward Bound."

David and Paul also reprised their roles as Starsky and Hutch with a cameo appearance in the 2004 movie remake, "Starsky & Hutch," with Ben Stiller and Owen Wilson.

Before his Hutch fame, David got started in Hollywood in the mid-1960s with small TV roles on shows like "Flipper," "I Dream of Jeannie," and "Star Trek" -- and, interestingly, Clint Eastwood was an early supporter of David's talent ... as he cast him as one of the cops co-starring with him in the 1973 Dirty Harry film, "Magnum Force."

He was also a very successful singer/songwriter ... scoring a number-one hit in 1976 with "Don't Give Up On Us."

David moved to the UK in the 90s and began starring in West End stage productions and British TV shows. He eventually became a British citizen in 2004.

He's survived by his wife and 6 children from previous relationships.

David was 80.