I think once you get nominated for a Best Actor Oscar, you fall off the "That Guy" list. :-) That disqualifies both of those guys.
It actually disqualifies David Paymer too (Mr. Saturday Night), but I'll let him slide.
I'd also take off Lisa Edelstein. It would be one thing if she stayed in roles like the prostitute who appeared briefly in 2 episodes of West Wing, but after 7 years as a lead on one of TV's highest-rated dramas (and for 5 of those 7 was THE highest rated), but there you go.
A couple I'd add:
M.C. Gainey. The FIRST SENTENCE in his IMDb profile says, "This threatening-looking, usually-mustached actor frequently plays hillbilly-type criminals." True. He had a 6 episode run on Justified, and 18 on Lost (he was awesome in most), but other than that, well over 150 single-episode stints and tiny movie roles. One of my favorites of those was Happy, Texas.
Brett Cullen. Like Gainey, he was on Lost and Justified...and over 100 others.
I'll try to think of others, but by its nature, this is harder to do than you might think....