First from a recent issue (#9) of the Incredible Hulk, written by Jason Aaron and Pasqual Ferry. The Hulk encounters a distant suburb of Atlantis where he meets...the Crab Riders!!
However, there IS such a thing as a GIANT barnacle! They live on whales... Here's an individual one..They can be about the size of a good sized beer mug..
and here's a bunch of them pictured living on a whale's rostrum (the front tip of the animal)
Also, while barnacles don't engage in "mind control" per se SOME barnacles are parasites and CAN actually control the reproduction of their hosts.. Here's a great little summary of the biology of these REAL animals by Casey Dunn at Brown University (via CreatureCast)
CreatureCast - Rhizocephala from Casey Dunn on Vimeo.