IMDB credits John Cazale for :-
The Godfather Trilogy,
Deerhunter,
Dogday Afternoon,
Godfather part 11,
The Conversation
and The Godfather.

He surely was a great loss to the acting profession, I believe he would have gone on to many more major parts and been a huge success as the leading man in all he did.
Bustas' post reminded me of Joe Mantenga, I tend to overlook him tho he has done quite a bit of other stuff in his career. I like him as an actor also. He has a distintinctive voice and he read The Godfather on my audio tape

FH