I don’t always find a revelation on these lists, but on this one I learned about a new-to-me bad guy, Henry Newton Brown. He was one of the Regulators.
These guys didn’t usually have a long lifespan. Brown was dead at 26. The linked article says he was hanged by a lynch mob, but Wikipedia says that although his three accomplices were hanged, Brown was killed trying to escape the lynch mob.
Ol’ Henry was unusual among these typically scruffy sidewinders in that he had movie star good looks, which raises the question of why he’s never been given significant representation in a Western. According to Wikipedia again, the only time he has been portrayed by name was in an episode of Death Valley Days, where he was played by rugged tough guy William Smith (who did resemble him).

Damn, these are all actual photos of them? Butch Cassidy looks like a Penn State linebacker. Or maybe one from THE Ohio State University.
If they ever do a remake, Butch should be played by Jesse Plemons
And Taylor Kitch as the Sundance Kid?
Good call!