Robert Duval, John Torturo, Jerry Orbach, William Devine.
Of course, Robert Duval went on to star in movies and even get an Oscar for Tender Mercies.
I think of a character actor as one that 's really good at his craft but does not necessarily became a star do to the fact that his image does not translate into a star. Often character actors are better actors than stars and not all stars are really good actors.
Robert Mitchum was lucky enough to have the image to go with his acting, on the other hand Robert Ryan didn't, although his performances were ceratinly great enough ( Wild Bunch ) for example.
Guys like Ernest Bognine and Lee Marvin did great work but were they more bankable than Cary Grant or Rock Hudson, no they weren't.
Hary Dean Stanton would be a great example of a great character actor that never became a star.
James Dean and Marlon Brando became stars from the get go.
Paul Newman could have been a bigger star if he hadn't been in Brando's shadow.
Kenneth Branagah can act circles around Tom Cruize, but is he a star?