Seriously, here he is in M*A*S*H*
Now, people might say that his career really kicked off playing Richard Nixon in the early eighties in Robert Altman's Secret Honor. Which might be true, it was a one man show with only him on the screen.
There's a whole host of places you might know him from. Such as playing Bookman, the library detective on Seinfeld.
This was probably his best scene (embedding disabled, sorry.)
He has a lot of authority figures under his belt such as:
The Police Commissioner in Ghostbusters II
The Attorney General in The Rock
In the nineties, he really hit his stride becoming one of the Paul Thomas Anderson players first with a more lead rule than usual
As Sidney(again) alongside John C. Reilly in Hard Eight.
Jimmy Gator in Magnolia
Floyd Gondolli in Boogie Nights
It's hard to find pictures of his stuff, but looking again through his IMDB page, its pretty amazing the amount of people he has worked with. He was in The Talented Mr. Ripley, The Contender, Zodiac, all 3 Rush Hour movies as well as:
Cradle Will Rock
and The Insider.
I guess it goes without saying but I find he is always a welcome addition to anything I am watching.