A DeviantArt user called “wytrab8” (real name: Hillary Smith) has creatively and excellently mixed pop culture characters with classic works, dubbing it Pop Reinterpretation.
The Muppet nightmare on the left is based off part of Garden of Earthly Delights by Hieronymus Bosch, while the Joker on the right is inspired by Portrait of a Child with a Drawing by Giovanni Francesco Caroto.
Browse all of Pop Reinterpretation here.