Sorry, bro. He is. He might not have won the 3 Oscars (totally vote loaded) that Brennan won, but he makes any movie better.
Don`t be talking `bout Walter Brennan now Doc..we`re friends but you`re about to cross a thin line buddy!
E, Fucking Emmet Walsh is da` man,great in every role he ever played.
Another good underated actor is Harry Dean Stanton.