Pony Head (voiced by Jenny Slate) -- Star 's best friend from Mewni and a floating unicorn head. She is described as sassy, sarcastic, and mischievous. She does not get along with Marco and is sometimes jealous of him when he interacts with Star. Nefcy said that Pony Head originated from an early story of Star where the latter was a fourth - grader and was discouraged during her attempts to recover a stolen bike; an image of Pony Head appeared and told Star not to give up.
who plays pony head on star vs the forces of evil
Jenny Slate