Whenever I tell people my daughter is named Fiona they almost always say, "Oh like on Shrek". While yes that is technically true she does have the same name as a character in those (crapalicious) movies but, no she was not named after a giant green ogre. That's not a comparison any mother wants made, thank you!
Actually it's an Irish name and is not uncommon in the British isles. We chose it because it was pretty and sounds good with our last name (which is also Irish). Not that we're all about being Irish, like most people these days we're mutts.
However to be completely honest I was inspired to add that name to my mental list of potential baby names by a character in the movie The Secret of Roan Inish. A really well made film about a family in Ireland who's fortunes have taken a down turn since they moved off the island of Roan Inish (island of the seals) after the loss of their young son. The daughter (Fiona)begins returning to the island and learning it's history and comes to believe that her brother isn't dead but being raised by selkies (seals that turn in to women). It's considered a family movie and it is entirely appropriate for kids but I'd say it was more philosophical than fantasy. If you're looking for something to rent this weekend pick it up, you won't be disappointed.