Whilst character actors have existed since the dawn of cinema (fans of the old Warner Bugs Bunny et al cartoons will recognise caricatures of popular character actors of the 30s and 40s, such as Peter Lorre or Edward G. Robinson, for example), the four most archetypal contemporary character actors are, in roughly descending order of fame, Ernest Borgnine, Harry Dean Stanton, the late Brion James and Lance Henriksen. As with Gene Hackman and Michael Caine, there is a film showing on television right this very minute with one of the above ('Escape from New York' even has two of the above).

Of the above, all but Brion James have had shots at the big time - Borgnine won an Oscar for 'Marty', the film 'Paris, Texas' was apparently written specifically with Harry Dean Stanton in mind from the start, whilst Lance Henriksen had the television series 'Millennium'. Brion James, on the other hand, is immortal for delivering the line 'Wake up... time to die!' from the film of 'Blade Runner'.

Each of the above have massive filmographies and have probably worked with more cinematic legends than most leading men - Stanton, in particular, has worked with Ridley Scott, David Lynch (several times), Terry Gilliam, Martin Scorsese, John Hughes, Alex Cox, Wim Wenders, John Carpenter and others.

Other popular character actors include William H. Macy, Steve Buscemi, Jean Reno, Sean Bean, the entire cast of The Usual Suspects, everybody in every spaghetti western not called Clint, and every Bond villain, Bond girl, henchman, MI5 officer and so forth. And everybody in those re-runs of Kojak, Quincy, Banacek, Colombo, Starsky and Hutch, all of it. Each of those people had lives and careers, hundreds, thousands of them, their mothers were proud to see them on television, but now they're just punk #2 or station junkie #12 or police sergeant #5. During the 1960s and 1970s there were character actors who specialised in playing Nazis, such as Anton Diffring and Karl-Otto Alberty, both of whom you would recognise on sight if not by name. Britain has produced James Robertson Justice, Ralph Richardson, Sean Bean and Terry Thomas, Sweden has given the world Stellan Skarsgard, France Jean Reno, whilst the female gender is represented by Celia Imrie and Julie Walters. There are many more male character actors than female, which is probably because women are seen as something of a commodity in Hollywood, as interchangeable Lego bricks.

It's worth noting that 'character' actors do not necessarily play the same type of character from film to film, or even characters on one particular side of the light/dark divide; on the converse, plenty of film stars and leading men play minor variations on their 'film persona', with the curious result that character actors are often more versatile than the people they support.

In the thespian ranking table, character actors are beneath supporting actors (such as Dan Ackyroyd, say, or almost all actresses, which is a sad thing but true), but above little people, giants, anonymous naked women, cute kids and other cinematic novelties.

For an interesting overview of these tireless performers:
http://www.dougmacaulay.com/kingspud/sel_by_actor_index_1.php