Eventually, You Get A 12-Person Villain Team

While "Octobliterator" is a good name for an angry octopus out to destroy the surface world, I think it also has potential for someone out to destroy everything associated with the month of October. It's also possible they could be using the power of October to attack others, but I'm sticking with the first interpretation.

So, Octobliterator. Probably loves hot weather and dreads the emergence of crisp falls days. Hates the changing of the leaves' colors. Hates Halloween. Hates the presence of pumpkin spice all over the damn place. Doesn't like corn mazes. Umm, what else is Octoberish? I tried looking up October holidays but there were like 500 of them and hell if I'm going to read through all those in an attempt to make up bad jokes.

You can go bizarrely comical with the idea. Have the Octobliterator trying to paint all the leaves green, or drive a giant combine through the corn maze from the entrance directly to the center. Dig up fields of pumpkins and plant summer squash. Or inundate the fields so they just aren't suitable for pumpkins. Maybe the Octobliterator is the one getting Christmas stuff into the stores earlier and earlier, in an attempt to squeeze out Halloween entirely. He or she (or they? perhaps it's an entire squad of Octobliterators) certainly give out travel-sized toothpaste things at Halloween. You wouldn't think they'd even celebrate it, but if they can't destroy it entirely, they'll take the opportunity to ruin the night for as many children as possible.

Or, go more serious. Octobliterator tries to delay the leaves changing by making the planet warmer (not that he or she would need to do much there), or by tilting the Earth's axis so the seasons vanish and plants don't have to respond to diminishing sunlight. Breed an insect that eats pumpkins, or introduce something into the air which makes the entire population allergic to pumpkin spice*. Open an impossible corn maze, wait until a bunch of people are in it, then light it on fire. Make people think they're super unsafe. Or get people in there and turn it into Murderworld.

* One of the Sinister Six stories back in the '90s involved Doc Ock releasing some compound into the atmosphere that would make it deadly for anyone to use cocaine, unless they got the antidote. Which only he had. So he could basically extort all the wealthy, coke-addicted '80s businessmen. Except the compound also would eat a hole in the ozone layer.