More than Shepard himself, even, I would venture James Gammon is the face of Sam Shepard's plays.
The playwright offers a moving tribute to one of his standby actors, who passed away last week:
"This guy walked on stage, and it’s as if everybody else in the play disappeared, as if he had stumbled in from an alleyway and just was this character."
(He also says something about he and Joe Papp fighting so much they were "oil and water"!)
Gammon in Steppenwolf's
1995 revival of Buried Child.