First Film - To Kill A Mockingbird
In 1969 he co starred with James Caan in their first Coppola movie The Rain People. Coppola would then cast Duvall in his next 4 films (The Godfather, The Conversation, The Godfather Part II, Apocalypse Now)
Duvall made it big in the 70s also in MASH, Joe Kidd, Network and Coppolas big 4.
Also had roles in The Natual, Colors, Days of Thunder, Falling Down, The Apostle, John Q, God's and Generals, Open Range, Secondhand Lions, and the last film I saw of his The Judge.
I missed a lot more but Duvall is an absolute legend in my book. One of the best supporting actors of all time. RIP