After hours of fiddling around with it, I'm done. Here's the cover. I'd like the main image to be a bit sharper, especially considering how long it took me to get all those characters posed just right, but I'll just have to settle for this because it's taken too long already.
Interesting fact: Jack Kirby CHEATED on the cover of Fantastic Four issue 1. There's no way to precisely replicate that cover in a 3D environment because the perspective is absolutely screwed up. Still, I think I did an okay approximation with what I had.
The Alyx model is a Reskin of the original Alyx. (Beware: it's a replacement model, so if you install it, you'll be seeing TF2-Alyx in the Half Life 2 maps if you play in Garry's Mod.) I was originally going to have BLU Spy where Alyx is, because Spy can turn invisible. However, I noticed that Sue is wearing a red dress on the cover of FF issue 1, and since TF2-Alyx isn't appearing in the story, I decided to give her a cameo on the cover.
The big guy holding onto TF2-Alyx is "El Gigante" from Resident Evil 4, the only model I could find that looks even remotely similar to the Mole Monster. I've cheated a bit myself with the Inflator tool to give him proportions more similar to the Mole Monster. I also had to shrink his legs down to get him to fit in the canyon. Just imagine he's kneeling.
I just noticed there's a stray thingy on the side of Heavy's speech bubble... I might fix this another day.