who does the voice over for her?
Cameron Diaz
Princess Fiona
Fiona is voiced by actress Cameron Diaz. 
when does princess fiona turn into an ogre At night who is princess fiona? Princess Fiona is a fictional character in DreamWorks' "Shrek" franchise is this a cartoon? No, an animated film what are the names of the other characters? Donkey, Shrek, and many more is there only 1 film or is it a film series? A film series how many films in total? 5
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Princess Fiona [SEP] Introduction
Created by screenwriters Ted Elliott and Terry Rossio, Fiona is loosely based on the unsightly princess in William Steig's children's book "Shrek!" (1990), from which her role and appearance were significantly modified. The screenwriters adapted the character into a princess under a shapeshifting enchantment, an idea initially greatly contested by other filmmakers. Fiona is voiced by actress Cameron Diaz. Comedian and actress Janeane Garofalo was originally cast as the character until she was fired from the first film with little explanation. Fiona was one of the first human characters to have a lead role in a computer-animated film, thus the animators aspired to make her both beautiful and realistic in appearance.