blood1, blood2: https://opengameart.org/content/bloodsplatter-and-bloodsplash-animation
by MoonStar

blood3, blood4, blood5: http://powstudios.com/content/blood-animation-pack-1
by Pow Studios

blood6: http://bigrookgames.com/portfolio-items/top-shooter-2d-sprite-animation-kit/
by bigrookgames

blood7: https://gifer.com/en/2pcT
by swordmane

splatter 1-7 https://opengameart.org/content/splatter-pack
by johndh