“Ronald Reagan Riding a Velociraptor,” by *SharpWriter on DeviantArt. You can buy prints of this image, and other awesomely weird works by SharpWriter, at his Etsy store.
FDR Transformer, Teddy Roosevelt Vs. Bigfoot, Abe Lincoln Riding a Grizzly, John F. Kennedy Alien Hunter on a Unicorn, George Washington Zombie Hunter—hoo-wee, there’s a lot to love. (thanks, Dingus!)