I've seen Cthulhu mods of My Little Ponies, but none as good as this one by deviantART user Cehualli. She writes:

Features wings, tentacles with suckers on the face and tail, cheek fins, and a sail going down the spine. Sculpted in apoxie over wire armature, painted with metallic greens, gold, and some blue on the feet, and covered with extra-creepy glossy sculpey glaze for a very wet look.

Link via Great White Snark