During the Credits
There is a short scene with a cameo as the credits start, followed by more background imagery shown during the credits of Split.
The stinger, which contains a cameo by Bruce Willis as David Dunn, connects the film to Unbreakable. Director/writer M. Night Shyamalan has confirmed that Split is in the same universe and plans to write a third film.
After the Credits
There is no stinger after the credits of Split.
Special thanks to Lisa DuMond and Scusi for the stinger submissions!