Ice Queen is a villain in Adventure time. Voiced by Grey DeLise, Ice Queen is a character created by Ice King in a Finn and Jake fan-fiction entitled Fionna and Cake. She serves as the main villain of Fionna and Cake and Five Short Tables, and as a minor villain in the comics.
In Fionna and Cake, during Fionna and Gumball's conversation, Cake's tail frizzes up, sensing incoming danger. Fionna rushes to the balcony and sees the Ice Queencoming down from dark clouds to kidnap Prince Gumball. She breaks into the castle, forms a slush beast around herself and goes after Gumball. Cake turns into a morning star that Fionna uses to smash the slush monster, with Ice Queen and Gumball inside. The room fills with snow, and Prince Gumball appears unharmed, but Ice Queen has mysteriously vanished. Prince Gumball then asks Fionna to "go out" with him, and Cake agrees for her to meet him again in an hour at the Castle Gardens. Later, he invites her to his ball as his date, but when he takes her to his room, a drop of water lands on her shoulder, she looks up to see the real Prince Gumball trapped inside a giant icicle on the ceiling. The fake prince is revealed to be Ice Queen, now taking off her disguise. Enraged by the deception, Fionna takes out the crystal sword to fight, but the sword is another one of Ice Queen's tricks and turns into a ball of ice around Fionna's hands. Cake hears noises from downstairs and senses Fionna is in trouble. Undaunted, Fionna uses the ice to beat Ice Queen over the head. Ice Queen pushes her off in burst of snow, which allows Fionna to get close to enough to break Prince Gumball free. Ice Queen gets knocked down by the broken icicle pieces just before Cake bursts into the room. Seeing Gumball standing next to Fionna in her torn dress, Cake jumps to the wrong conclusion and lunges at the prince. Fionna stops Cake from hurting Gumball and tells her it was the Ice Queen all along. Just then Ice Queen recovers and blasts Cake away from Fionna with a torrent of icicles. Fionna knocks her magic tiara off, squelching her powers, and then punches her for "yanking her heart-guts." Cake then uses the tiara's power to bury the Ice Queen in snow.
In Five Short Tables, at the Ice Kingdom, Ice Queen reads to her penguins the story of Ice President reading his own fan fiction to Flynn the human being and Jacques the Raccoon. When she finishes, she asks the penguins how they liked it and becomes upset when she sees that they are all distracted by Cake's flapjack art. Cake offers to make a flapjack portrait for Ice Queen, but she reluctantly refuses and begins to attack Fionna. Cake uses her newly developed pancake skills to make Fionna a flapjack sword. While Ice Queen and Fionna attack each other, Fionna compliments Ice Queen on her story before deflecting an ice beam that freezes the queen. Cake puts a flapjack face on top of Ice Queen's actual face and leave.
In Issue 16, it is revealed that Ice King created a real life, giant Ice Queen to put in his dungeon, which he abandoned 200 years ago. When they meet again, Ice Queen rebuffs him and attempts to kill Finn and Jake; however, Ice King flies through her chest, causing her to shatter to pieces. This also frees an old lady Ice King used to power her "secondary regality processor."