It gets lost in his filmography because it's unlike most of his other movies, but people often forget he directed The Omen. That movie still holds up incredibly well and is one of my favorite horror films of the 70's. Inside Moves is a lesser known movie of his that is pretty good as well. Ladyhawke is another rock solid underrated movie from Donner
The guy had a hell of a resume and is one of the most important directors of the 70's and 80's that often doesn't get mentioned as being important. His 90's run isn't as good, but he was a big part of Tales From The Crypt and directed one of my favorite episodes called The Ventriloquist Dummy starring Don Rickles and Bobcat Goldwaithe. The western episode he directed called Showdown is also very good.
RIP