Slime Princess makes her appearance in "Prisoners of Love" where she is kidnapped by Ice King. She showed a lot of affection to Finn, even going as far as saying she wants to marry him for saving her and the other princesses, or at least until Jake told her that Finn "wets his pants constantly, all the time." She reappears in "Loyalty to the King," where she is the first princess to meet and befriend the "Nice King" in the park after misinterpreting his real name. And she again appears in "Video Makers" where Finn decides to use her in a scene for his movie where she does stunts around a river filled with alligators. Though she accidentally fell in the river, she ended up kissing the alligators instead of getting killed, ruining the scene for Finn. She also appears at the premiere of the film at Finn and Jake Movie Club. She is the ruler of the underground Slime Kingdom.
Slime Princess looks just as she sounds, like a glob of slime. The majority of her body is dull lime-green color, but she also has a yellow center. She has two arms, that when not being used may disappear back into her body. She wears a tiara similar to that of Princess Bubblegum, only the gem in the center is green, while Princess Bubblegum's is turquoise.