Marshmallow's general shape and structure looks like the rancor! I can't believe I didn't see it before. DeviantArt user choosecheese127 spotted the similarities after he saw the film and made the above image, and I think some inspiration was definitely pulled from Star Wars. Just a bit maybe, but I love seeing it.
I don't write fan fic, but if I did, I'd want to write an adventure starring Marshmallow and Jabba's rancor. I'd probably have to bring in Olaf for a musical number.