A Shrek Theory

It's no secret that half of the cast of the Shrek movies is made up of parodies of our favorite Disney characters. But what about Shrek, Fiona, and Donkey themselves? Are they parodies of any particular characters?

Personally, I believe that Shrek and Fiona are parodies of the main characters of Beauty and the Beast. Think about it... A human being falls in love with a monster. The one difference is that here, instead of the monster becoming a human, the human becomes a monster. Heck, Fiona's transformation at the end of the first movie looks very similar to the Beast's!
Now, with her red hair, it's possible that Fiona is intended to be a parody of Ariel from The Little Mermaid. But a mermaid clearly intended to be Ariel appears at the beginning of the second film, so probably not.

As for Donkey... Well, he's a donkey. As is Pooh's pal Eeyore. Is Donkey an Eeyore expy? Probably not. Although there is a theory out there that he's one of the kids from Pinocchio who made the mistake of going to Pleasure Island...

Or maybe I'm just looking too hard into it. What do you all think?