Cuber

Cuber speaks in the beginning and end of the episode, "Five Short Graybles. He seems to know Fionna, Cake, BMO, Tree Trunks, Marshall Lee, Gunter, and Prince Gumball but calls Ice Queen "the blue lady" and Lumpy Space Prince "the other thing." He may be from the future, considering that he says the stories seen in "Five Short Graybles" are tales from "the days of old." This can be supported by the fact that his clothes and room look advanced, though similar technology can sometimes be found in Aaa. He speaks a variety of non-English terms (see quotes) but mostly speaks English.

Appearance
Cuber's skin is light pink, and his head is significantly larger than the rest of his body. His facial features are similar in appearance to most characters', albeit spread apart across his large face, leaving him with a comically small mouth in proportion to his other body parts. He wears a little hat with a small, spinning purple cube that floats next to it. The hat itself is a hemisphere with a small, bent rod coming from the top. The hat is the same color as his robe, which is light salmon colored. His robe has small green, mauve and light blue squares on its front top half. Its chest also has a line with many 90 degree angles that dividing it approximately down the middle. The line ends abruptly at the beginning of the bottom half of his robe, suggesting that the top and bottom halves of his robe could be separate.