if so why is he considered the greatest working actor from the classics era who is most relevant for modern viewing by both Scorcese and Ebert. They both put him above the likes of Stewart, Fonda etc.
I think he was the king of the noir genre and once the genre died in the late 50s he had to diversify. His westerns indeed are poor in comparison and its surprising considering his frame, his childhood and his image as a mans a man; he should have thrived in the genre but never did.
Great question, Greatstreetwarrior, and I think that Mitchum's iconic status is a rare case of a star sort of growing in stature as the years go by rather than having a great era, the way most classic era stars had. Mitchum was "rediscovered" in the Sixties, and I think that the rise of the youth culture of the period, plus the far greater posthumous mega-superstardom of a certain Mr. Bogart helped fuel Mitchum's reputation as a WTF anti-establishment guy, this some years before Jack Nicholson hit big.
Fact is, Mitchum wasn't quite what the kids who dug him thought he was. A beatnick? Sort of. But a Republican beatnick (true). Mitchum's screen persona was that of a rugged individualist who lives by his own code. He was versatile enough to do other things, didn't limit himself to one type of role, but that was the essence of Mitchum as a star; and it's also what he shared with Bogart.
As to Mitchum's being a
Noir king, okay; but they didn't call those kinds of movies
Noir back in the Forties-Fifties, so basically a more accurate way to state is that Mitchum did well as an offbeat star of crime films. Mitchum's many years with RKO was a blessing and a curse: a blessing because that studio was itself offbeat, made many oddball and artistic films, was in some ways a perfect fit for non-conformist Bob Mitchum. On the other hand, once Howard Hughes bought the place it became a joke. Not overnight but in a few short years.
Another interesting Mitchum factoid: he was never truly a top mainstream star. In his heyday he was one of the many go-to guys for the studios and indie producers to, well, go to, when the top names (Holden, Brando, Lancaster, Hudson) turned a project down Mitchum was one of the first of the second tier stars to be sought out; maybe a notch below Richard Widmark, a notch above Jeff Chandler. A good position, for sure, but at the time he didn't seem to have the makings of a screen legend, though he did appear in more offbeat films than most; and
Night Of The Hunter and
Thunder Road were truly offbeat fare, with the later proving a major hit.