I watched The Hunter Red October last night, and thumbing through IMDB found that Admiral Padorin was played by Peter Zinner in his one and only acting role.
The role is a significant plot point if not a long scene, Admiral Padorin opening a a letter from Ramius confirming his intention to defect.
However But Peter Zinner should instead be remembered as a film Editor, including The Deer Hunter, The Godfather, and An Officer and a Gentleman. All 3 brought him Oscar nominations and he won Best Film Editing for The Deer Hunter.