Favorite character actors?

[Groo The Perverted]

EDIT: ALLOW ME TO BE SPECIFIC. I AM REFERRING TO TELEVISION CHARACTER ACTORS. AND NOT PEOPLE WHO GET STARRING ROLES REGULARLY, I MEAN "GUEST APPEARANCES" KIND OF PEOPLE, WHO OCCASIONALLY MAY GET LARGE SUPPORTING ROLES.

NOT MOVIE ACTORS

We all have favorite character actors, who show up a lot as "guest star" roles, and perhaps even gets a role on a long running show.

Who are yours?

These are, in my opinion, three of the best character actors working today.

Garrett Dillahunt (Terminator: Sarah Connor Chronicles, Deadwood, 4400, Life)



Robert Knepper (Prison Break, Carnivale, Heroes)



Michael Emerson (Lost)