Post-credits scenes have become increasingly common in recent years, but they’re certainly not exclusive to the present day. The earliest one I can remember was in the live action adaptation of Masters of the Universe, released in 1987. The post-credits stinger teased that Skeletor is still alive… though a sequel never followed.
As for horror movies that have had notable post-credits scenes, they include Zombieland, Curse of Chucky, Cult of Chucky, and Fede Alvarez’s remake of Evil Dead.
Another horror movie that *almost* had a post-credits tease? The Lost Boys!
Reported by io9 today, the sold out book Lost in the Shadows: The Story of The Lost Boys includes an except from the original script for The Lost Boys, laying out the gist of the post-credits scene that was ultimately axed when the budget was significantly cut. According to the book, the scene “never got past the discussion stage.”
The scene would’ve returned to the underground vampire lair, after Grandpa helps kill Max and the end credits have finished rolling across the screen…
INT. LOBBY/CAVE – NIGHT
Deserted, the CAMERA PROWLS through the Rock ‘n’ Roll ruins.
Eventually the CAMERA pushes toward the old mural painted on the lobby wall. The mural depicts a typical day on the boardwalk in the year 1900.
CAMERA MOVES CLOVER AND CLOSER TO THE MURAL
And HOLD TIGHT on one painting figure in particular. A man in a straw hat. He’s grinning broadly…and he’s most definitely Max. He’s talking to a group of young men.
Without seeing an image of the mural itself, which was never actually created, it’s hard to know what the post-credits scene would’ve hinted at, but it seems it was simply going to suggest that Max had been around for a very very long time. We can only assume that the “group of young men” depicted in the mural was to be David and the gang.