Not sure if these are the types of mash ups or re-imagining that you’re into…but may inspire some ideas:-
Supperman – fat slob eating cold pizza and pies (Homer, Peter Griffin, Jabba the Hutt)
Fatman – as above
Whole range of heroes that could be drawn as their names describe, but do as a caricature
Robin – cute, like on a Christmas Card
Pengiun – can evil and cute be mashed together (think ‘Happy Feet’ crossed with Danny Devito)
Spiderman – but as a house spider stuck under an upturned glass or stuck by the plughole in a bath, a very unglamorous situation for a ‘hero’
Cyclops – but Leela from Futurama
Greedo as the Grinch who stole Christmas
Doc-ock – but Zoidberg from Futurama
Bullseye – mash up of Bully from Bullseye (of Jim Bowen fame) and Bullseye (like in Daredevil)
Silver Surfer – OAP
The Flash – doing a cheesy advert for Flash cleaning liquid
Doctor Doom and Gloom – Mo from the Simpsons
Green Lantern and Jamie & His Magic Torch
Ghost Rider and Jasper the Ghost (although I’m not convinced with this one)
Avatar – mash up the 2 films into either one character or each character appearing in the wrong film (set)
And I’m sure there’s an idea with Jenga Fett

That’ll do for now…