The closest John Wayne came to playing a villain, in my memory was in "Reap the Wild Wind",
but even there he redeems himself at the end of the movie.
Although the real villain is one of the greatest villains in all cinema Raymod Massey.

The funny thing about this movie was that when it was originally released Paulette Goddard got top billing,
but shortly after Ray Milland won his oscar for "The Lost Weekend" it was re-released with Ray Milland getting star billing,
and somewhere along the line there was a third release, with John Wayne getting top billing.
Not sure if that was between the two or later still, but I know I have seen all 3 getting top billing,
which I thought was really strange.