...a monster of vaguely anthropoid outline, but with an octopus-like head whose face was a mass of feelers, a scaly, rubbery-looking body, prodigious claws on hind and fore feet, and long, narrow wings behind. This thing, which seemed instinct with a fearsome and unnatural malignancy, was of a somewhat bloated corpulence, and squatted evilly on a rectangular block or pedestal covered with undecipherable characters. The tips of the wings touched the back edge of the block, the seat occupied the centre, whilst the long, curved claws of the doubled-up, crouching hind legs gripped the front edge and extended a quarter of the way clown toward the bottom of the pedestal. The cephalopod head was bent forward, so that the ends of the facial feelers brushed the backs of huge fore paws which clasped the croucher's elevated knees.(from "The Call of Cthulhu" by H.P. Lovecraft)
It's a fairly descriptive paragraph by Lovecraft, and about 10 days ago Ectoplasmosis posted an picture that Lovecaft drew himself of Cthulhu, though it's hardly as fear-inspiring as many modern ones we see. I like that the link talks about the eyes...apparently clustered and spider-like vs. what is normally seen today, though I haven't seen any story text in "TCoC" to indicate they are spider-eyes. Spider-like eyes would add such an incredibly alien character to Cthulhu though...which is probably closer to the intent.
There is a further wealth of images of Cthulhu and mythos-related monsters and some film shorts here as well. Scroll down, lots of good pics.
There's yet another image and a lengthy explanation of Cthulhu, the mythos, and its impact on pop culture etc at How Stuff Works. Interesting picture on the first page...not much of a bloated corpulence there...I think Cthulhu had been hanging out with Brian McNamee and "Raw-jah" for a while.
Still, to each his own. This artist has the bloated corpulence down, but has undersized the wings a bit, methinks. It's still funny as Hell. I hope he produces something new soon.
Or, you could just dress your kid up and take a photo of his non-plussed ass...
Unconnected to the above, but still with roots in Lovecraft and the Mythos, briwei took the time to point me toward the web comic Shadowgirls by David Rodriguez and Dave Reynolds, about a mother-daughter team who discover they have "dark powers" as evil creatures invade their home town of Innsmouth. It's been running for a while now and there's a lot of it I haven't read, but I always dug girl fights. Magical ones are even better. Interesting the mother's name is Charon...