So I've shared various Cthulhu related images and objects in the past. But they've mostly been cutesy or jokey versions of The Great Old One. Which while fun and cool isn't quite in the spirit of the source material. Lovecraft after all was undoubtedly writing horror stories and christmas tree tentacles aren't that horrific.
So in an effort to balance the scales a little I give you this image by glooh which shows a suitably imposing vision of Great Cthulhu rising from the water.
You would not want to be on a ship when this guy showed up.
Source: Deviantart — Cthulhu by glooh