Arguably the best pitcher of the first half of the 20th century (I'd put Mathewson, Alexander and Grove in the equation) and equally arguably the best right hander of all time (with Mathewson and Alexander again, together with Clemens)
Johnson was one of the first pitchers to throw hard all the time, instead of just bearing down when he needed to, as was the practice of most pitchers in the dead ball era. He had an unusual sidearm motion, that in the jerky films of the era looks like his arm should have fallen off by the sixth inning of his first game.
Still the career leader in shutouts with 110, a record that looks likely to stand another century.