Whenever someone thinks about silent cinema the image of the laughing villain, twirling his mustache, and tying the hapless blonde beauty to the railroad, pops up in our collective memory. But in which movie (or movies) did that particular image first appeared?
The link in Neil Baker's comment to Luke McKernan's "Tied to the tracks" article also gives a very detailed history of a woman being tied to the tracks, occasionally by the evil villain twirling his moustache.
Luke traces it back to an 1867 staged melodrama by Augustin Daly called Under the Gaslight, where a woman saves a man from the tracks in the nick of time. Later plays copied this, and at some point it switched to a man saving a woman.
In early film, such stage melodrama was out-of-date -- "so no more twirling of moustaches if you wanted your villain to be taken seriously" -- and instead film capitalised on recreating realism.
However films such as 1905's The Train Wreckers and 1911's The Attempt on the Special played it straight, where an unconscious woman is left on the tracks. But she was left there by a gang rather than the moustachioed villain.
The black moustache-twirling villain, often enshrouded in black and with a top hat, and the heroine in distress are two of the six stock characters of Victorian stage melodrama:
This made me think of an 1913 movie that Mack Sennett made called Barney Oldfield's Race for a Life. If I recall correctly, this film featured not only a mustachioed villain, but a woman tied to the train tracks!
Possibly the earliest version.