|Introduced In||Adventure Time with Fionna and Cake|
|Voiced by||Madeleine Martin|
Fionna (previously named Fiona) is the female counterpart of Finn, created by series character designer Natasha Allegri in a series of web comics and drawings. She and the other gender-swapped characters will appear in the season three episode "Adventure Time with Fionna and Cake". She is usually seen in the company of her own stretchy companion, Cake who is the gender and species-swapped version of Jake. Fionna's enemy is the gender-swapped version of Ice King, the Ice Queen.
She wears an outfit similar to Finn's: a rabbit-themed hood (opposing Finn's bear-themed hood), exposed locks of blonde hair. Unlike Finn, she has her neck exposed. She also has a sky blue shirt with longer sleeves than Finn's, and a dark blue skort (a mix of a skirt and shorts); this was confirmed on Natasha's formspring. She has a lighter shade of blue than Finn's clothing, the same green backpack, athletic, knee high socks that have two blue stripes at the top, and Mary Jane shoes on her feet. In the Ice Kingdom, she wears a Yellow sweater. She also wears red pajamas.
- Her name was officially changed from "Fiona" to "Fionna," presumably to make it more similar to Finn's name. Pronunciation, however, remains unchanged according to Natasha Allegri.
- Like Finn and his crush on Princess Bubblegum, it is revealed in many portraits posted that Fionna has a crush on Prince Gumball.
- In some portraits posted, Fionna, similar to the way Finn has missing teeth, she has buck teeth like a rabbit. In the actual episode, though, these are absent.
- Revealed on Natasha Allegri's formspring account, the dress she designed for Fionna is based off Princess Serenity's dress from the anime, Sailor Moon. This may also be the inspiration for Fionna's rabbit-themed hood, Sailor Moon's protagonist is named "Usagi," which is Japanese for "rabbit." Usagi, or Sailor Moon, also has a talking feline companion named Luna.