You can pry my em dash—short for "Emily's dash", after the poet—from my cold dead hands.
https://en.wikipedia.org/wiki/Caedite_eos._Novit_enim_Dominu....
Until that relatively recent shift, it was named the Morse Dash—you'd think because of the "long" glyph when rendering Morse Code, but no, it was named for the 17th century English Catholic martyr Henry Morse, for reasons lost to time.