He was great in The Apostle. It made a great sermon
He made that movie with his own money. Favorite scene:
BillyBob Thornton played a troublemaker who did not like nigras and white people worshipping together. When The Apostle took him out of the church to lay an ass whoopin' on him, he says, "Come on son; I don't even the Lord's help for this."
And proceedes to whoop his ass.
Duvall also did a cameo as Carl's Daddy in Sligblade. The 15th Anniversary has a wonderful special feature of Billy Bob talking about how that came together - not just Duvall, but the whole making of that awesome movie