O is the Slime Elemental 1000 years in the future. O can be seen taking cover after X shoots at them in the "Come Along With Me" intro sequence.


O is a chubby, slime humanoid who has a slime "O" surrounding their face. Tiny specks can be seen inside of O's body.


O is the Slime Elemental, therefore they have the power to control slime.


  • According to Steve Wolfhard, O was included in order to give closure on Slime Princess.
  • O's name, along with X's, may be a reference to the game Tic-tac-toe (also known as Noughts and Crosses), with  and O representing the noughts, and X the crosses.



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