This is one of my favorite things I've seen in a while. Toward the end of a 34-win 1912 season, Smoky Joe Wood received this letter threatening his life.
Wood's 1912 for the Red Sox was one for the ages. Of the 38 games he started, he finished 35 of them. Bugs And Cranks, which dug up this gem, say he received a number of threats that year, presumably from opposing fans trying to rattle him. This one, sent to his hotel before a four-game series with the Cleveland Naps, didn't work: box scores don't survive, but Boston swept the series.
I wonder if the threat lost some of its menace when the anonymous author made his alterations in the text rather than start over again.
Want to See a 100-Year-Old Death Threat Mailed to a Pitcher? [Bugs And Cranks]