Olmos has a certain gravitas. His face just gets craggier and scarier all the time.
I always liked how he credits BSG for being the greatest role of his career. He knows he'll never get a part like Adama again.
Gandolfini knew there'd never be another Tony Soprano on his resume. McShane knows he's seen the last of the likes of Al Swearengen. Bryan Cranson understands Walter White was his magnum opus. It's just the way it is. All downhill from there, most likely. Lightning seldom strikes twice.