The 15 Second Horror Film Challenge is an international ultra-short-film competition. For more information see http://15secondhorror.ca. There you can also find out about the 2018 competition, open now until October 15.
Below are my personal favorites among the top 20 of the 2017 edition. I prefer eerie to bloody, but be warned brief gore (and a tiny bit of mildly foul language) can be found in some of the films below. I've arranged them into a viewing order that seems appropriate to me but that reflects neither by my relative rating nor the placement in the competition, though the latter can be found at the top of each video.
Paradox by Shahzad Ali
Emma by Daniel Limmer
Free Fallin by Derek Bensonhaver
Good Night by LUMA Films
VR by Richard Addlesee
Making Faces by Andrew J.D. Robinson
Bad Timing by Cameron Fife