Even though this concept isn't 100% original -- Conan's "If They Melded" segment did it first, after all -- these celebrity face mashups are so clever/ absurd/ terrifying we couldn't resist their bizarre charms.
Every week, the FaceMashups YouTube channel releases a new video of anomalous celebrities melted together using fancy motion-graphics editing -- and the results range from the brilliant (Zach Galifianakis and Kristen Stewart, for example) to the ludicrous (Kate Upton and Louis C.K.) to the nightmarish (like this one of Adolf Hitler and Ann Coulter.)
FaceMashups sometimes chooses its subjects by popular vote, so if you have a good idea, let them know!
Click the videos to watch, and see the channel for many more examples.