A filmography as long as your arm.

THX 1138 for me. He's great in everything, but that's such an amazing performance, with minimal dialogue. He's so focused and believable and the setting is so surreal, without any explanation being given regarding what's even meant to be going on, that the whole movie rests on his shoulders. Everyone in it gives a standout performance, IMO, but Duvall is mesmerizing in that movie.

He has done an amazing amount of work over the years--and generally highly regarded work. I put down "True Grit."

Not among his best roles, but worth mentioning--he featured prominently in two original "Outer Limits" stories, one of which was the series' only two-parter. In "The Chameleon" he plays a government agent who disguises himself to infiltrate an alien spacecraft and see what they're up to. In "The Inheritors" he's a lawman trying to find out what some disturbed veterans who have begun manifesting superhuman abilities are doing.

His best performance was as Augustus MacRae in LONESOME DOVE, but since that was a television miniseries, I chose OPEN RANGE as his best film.

While my favorite Duvall character is Lieutenant Colonel William "Bill" Kilgore from Apocalypse Now but his greatest role was his movie right after called The Great Santini. The Great Santini received two Academy Award nominations: Best Actor in a Leading Role (Duvall) and Best Actor in a Supporting Role (O'Keefe).