Hey, It's That Guy!: The resemblance of human Shrek to (dour Scottish) British politician Gordon Brown was widely noted by the British media.
Hey, It's That Voice!: Averted — regardless of who you think Gingi, Pinocchio, the Magic Mirror and even Big Bad Rumpelstiltskin sound like, they're all voiced by animators. In a positive case of Executive Meddling, the execs liked the animators' temporary voice tracks so much that they let them "act" in the movie.
The film was originally going to be produced by Steven Spielberg, be hand-drawn, and star Bill Murray as Shrek and Steve Martin as Donkey.
The original script had Princess Fiona born an ogre to the late King and Queen of Duloc. They had her locked in the tower under the lie that she was "of such rare beauty" she was kidnapped. They died, and the kingdom was left under the rule of an ambitious regent (implied to be Farquaad). When she 'became of age' to ascend the throne she escaped the tower and encounters a witch named Bib Fortuna (a reference to the Star Wars character of the same name) - who has narrated the entire sequence through her tarot cards. She gave Fiona a potion which would make her beautiful; but Fortuna warns her the potion has a side effect - she will change between her human and ogress form until she finds her true love. Later she was whisked away by her dragon guardian and returned to the tower. This storyline was not adapted to keep the story simple, but is mentioned through the "witch" Fiona tells Donkey about.
Chris Farley was originally cast as Shrek and even recorded part of the dialogue - however, after he died, the role was given to Mike Myers.
Steve Martin was considered to voice Donkey.
Also, wasn't Paul McCartney in talks to voice Rumplestiltskin?
