His wife, Sian, shared the sad news with THR Saturday ... saying BH had passed away a few weeks ago at a hospital in Van Nuys, CA after suffering a heart attack.

Hopkins had some legendary roles throughout his 7-decade career ... mostly carving out a rep as a supporting actor and a great on-screen villain/scoundrel, especially in 'AG' -- where he played Joe, the leader of the Pharaohs' greaser gang at the center of the flick.

'Graffiti' certainly helped put Hopkins on the map, but he'd already been making a name for himself in earlier films -- including a standout performance in "The Wild Bunch," where he played one of the zany outlaws looking to pull a big heist.

There were several other movies in which Hopkins left his mark -- including "Midnight Express," "The Getaway," "The Killer Elite," "The Nickel Ride," "The Only Way Home," "The Man Who Loved Cat Dancing," "Posse," "A Small Town in Texas" "Tentacles" and "White Lightning" -- just to name a few.

He also had a lot of TV roles as well -- having appeared in hit shows such as "Doc Elliot," "Hawaii Five-O," 'Mod Squad,' "Bonanza," "Gunsmoke,"  "Manhunter," "Barnaby Jones," "The Rockford Files," "Charlie's Angels," "The Fall Guy," "Dynasty," "Murder, She Wrote," and others.

Hopkins kept working well into the 2000s -- sometimes even doing voice acting, but for the most part, stuck with gun-slinging characters -- and his last job was in 2020's "Hillbilly Elegy" opposite Glenn Close and Amy Adams.

All in all, he's got over 130 acting credits under his belt ... and is regarded as one of the great supporting actors of his time.

Bo was 80.