By the 40s, comic book writers used it all the time. The original appearance of the Joker had him falling to his death (the writers, realizing they had a good thing, rewrote it with a line to indicate he was only partly dead). Alfred Bester once described writing for comic books with someone saying “And he’ll fall off a cliff or something” with the indication that this was a standard way of dispatching the villain.
It goes back a while.
The Bible contains two totally different accounts of the death of Judas Iscariot. The more famous one describes how he went and hanged himself in a fit of remorse. However Acts chapter 1 tells “Now this man purchased a field with the reward of iniquity; and falling headlong, he burst asunder in the midst, and all his bowels gushed out.”
Falling headlong is usually taken to mean falling off a cliff, and being dashed on the rocks below. Except by literalists who insist that it means hanging.
I have a theory that this is also the origin of “bought the farm.”
Is that more dead or less dead than “mostly dead”?
Sherlock Holmes’ archenemy, Professor Moriarty, perished when he fell from Reichenbach Falls. (Holmes died there, too, but he got better.) The story was published in 1893.