'MacGyver' Villain Michael Des Barres -- I'm the One Scared for My Life Now!

Michael Des Barres played master assassin Murdoc for several years on "MacGyver," but now he's afraid for real because of threats to kill him and his family.

Des Barres began receiving messages on Facebook last November from a fan who claimed to be sick. Des Barres engaged in "short positive responses wishing her well" ... but the messages got disturbing ... this according to a search warrant obtained by TMZ.

The docs also show that Des Barres eventually blocked the fan ... but the fan began creating new accounts and sending even more disturbing messages, including:

-- "I'm going to cut your throat a**hole!"
-- "They're going to f*****g kill you, you are all f****d, your all in danger your ex, parents and child."
-- "Your dead f****r, People will never stop harassing you and I'll cut off your d***.

One message contained a photo of a person who had shot himself in the head.