According to an anchor for local Hawaii outlet KITV -- who described Taylor as a family friend ... Taylor died Thursday. KITV did not provide a cause of death.

Television producer Peter M. Lenkov confirmed the news on his official Instagram account ... posting a picture with Wily from behind the scenes of a television show and telling his followers he's "heartbroken.".

Lenkov says he'll provide more details in the days to come ... but is far too emotional now to discuss his longtime friend's death.

TW -- born Teila Tuli -- started out as a sumo wrestler in the late 1980s -- becoming a rare example of an American joining the prestigious Japanese sport and reportedly compiling a 57-27-14 record over the next two years.

Wily also fought in a different arena ... slugging it out in one bout in the then-new UFC 1 -- and, he's the first fighter to ever lose a UFC brawl.

Taylor didn't actually start acting until the mid-2000s ... when he landed his breakout as Kemo in the Jason Segel movie "Forgetting Sarah Marshall."

Two years later, he got his part as criminal informant Kamekona Tupuola on 'Five-0' a role he played in 171 episodes. He reprised the role in the shows "Macgyver" and "Magnum P.I."

Taylor's survived by his wife Halona and their two children.

He was 56.