Cthulu is not a football player, but a hellish creature that stalks the souls of the tormented. However, had Cthulu of been a football player, then it would have been very good. It's aerial abilities would be a fantastic attribute, being able to jump several hundred stories into the air, and it's powerful shot able to pierce football nets, as well as hearts.
Cthulu most probably would have signed for a club like Preston, and then built it's way up to the big leagues. Cthulu had always scorned both La Liga and Serie A, so it seems likely it would have settled for a Premier League Club. Cthulu would probably have the record amount of goals scored in the preamier league, as well as most recorded fatalities.