Boone Helm was a bad man through and through. Born in Kentucky in 1828, he moved West for opportunity and mayhem. He reportedly murdered several men over the next 36 years—and, according to his own accounts, ate some of them to boot.
At various points, Helm was arrested; at one point, he was confined to a mental institution. But he always escaped or bought his way out, allowing him to continue his terrible ways.
Helm made it to Montana for the gold rush but was hanged by the vigilantes in January 1864.