Wolf-Spider
Peter Parker is bitten by a radioactive spider. He discovers his powers, as normal, and goes through the usual origin. One catch: Uncle Ben isn't shot. He's ripped to death by some sort of wild animal on the night of a full moon. Peter puts on his costume and tracks the creature to an abandoned warehouse. They fight, with Peter receiving numerous cuts and bites. As the fight goes on, Peter is forced to defend himself to his utmost, and manages to snap the creature's neck. The creature's neck bones and vertebrae heal almost instantly, and the fight is on, again. Peter tries to retreat, but the monster won't let him, and they gradually make their way from warehouse to warehouse, shop to shop, each one throwing the other one through walls and other things. In a jewelery shop, Peter uses the last of his strength to try and garotte the thing to death with the closest thing he could grab: a silver-plated chain like the guido-wannabes enjoy wearing. He takes the creature's head off. As he lies there, panting and waiting for the creature to heal, Peter observes the hair, claws, snout, etc. of the head and body changing into something all too familiar. It's the thief he could have stopped earlier! Under the light of the full moon, Peter realizes how badly he fucked up, and swears to Uncle Ben that he'll use his powers responsibly from now on.
Spider-Man becomes the toast of New York…for a month. Then, on the night of the next full moon, Peter realizes that something has gone horribly wrong as the fangs, claws, hair, etc. reappear. Due to a quirk of the radioactive spider, Peter becomes a wolfspider-man, rather than a wolf-man. Moreover, he retains his intellect and awareness in this form, but his visage is too grotesque to ever be considered a hero. He has unbearable cravings for human flesh, and he decides to sate them on the most deadly of criminals. So Peter designs another costume, one that allows for his extra arms and also hides the bloodstains.
For most of the month, he's your friendly neighborhood Spider-Man, stopping purse-snatchers and bank robbers. For the days of the waxing and waning of the full moon, he is Wolf-Spider, the creature in the dark that hunts the deadliest prey it can find.
>pic semi-related, only with a completely different costume and an actual wolfspider's head.
And if I see any of the above appearing in a comic any time soon, someone had better either try to get me some money or prepare for an ass-fucking with their own femur.