I was recently reminded of Joe Morton by Fametracker. They’ve got an amusing section entitled Hey, It’s That Guy, dedicated to all those actors who you recognize but never know the names of. Morton personifies this phenomenon for me, as he’s the guy who always plays the scientist or doctor. From Fametracker’s profile:
If Joe Morton never had another acting gig ever again (and let’s not tempt the gods by considering that idea for very long), his face would always be remembered for one particular role: that of Miles Bennett Dyson in Terminator 2: Judgment Day. He was the unwitting ruiner of humanity, the man behind the computer that would one day destroy us all, and who was taken hostage, along with his family, by the commando team of Linda Hamilton, Edward Furlong, and that big robot guy.
If you check out his IMDB profile, it’s full of scientist, doctor and government official roles. He’s the Ben (“We need a generic Middle Easterner, stat!”) Kingsley of brainiacs. He’s our cultural Professor Frink.
DarrenBarefoot.com 
The Sports Guy on ESPN recently watched a movie (61*) that had a whole whack of That Guy roles – http://sports.espn.go.com/espn/page2/story?page=simmons/movies/61
The interesting thing about HITG is the list of Asian actors. It’s always the same handful of guys (and gals), like James Hong (http://www.fametracker.com/hey_its_that_guy/hong_james.shtml) who seems to get those sophiscated Chinese villian roles.
First saw Joe in John Sayles’ “Brother From Another Planet.” Worth a look