- “When I was a baby horse, Mama told me the day will come when I will be called upon to fulfill a responsibility greater than myself, greater than this dimension. For me, that day is today!”
- ―Millhorse (speaking Italian)[src]
When healthy, this Millhorse has a white coat, starry pink mane and tail, green horn, and a heart on its chest. The head is similar to Pony Head's. When tired, it becomes thin and ragged, its coat is mostly grey, its mane, tail, and horn darken, and the mane and tail go limp, while the heart on its chest looks broken.
In "Storm the Castle", the Millhorse is killed when Star casts the Whispering Spell to destroy the wand. Its ghost is last seen leaving the wand and whispering in Star's ear before disappearing.
At the end of "Storm the Castle," the first Millhorse is replaced by a second one as part of fulfilling its "responsibility." This Millhorse is more mature-looking and has a gray coat, a greenish-gray mane which it pulls back into a ponytail, a dark blue shirt, yellow and black bands around its hooves, and a detachable horn. This Millhorse is also notable in that it speaks fluent Italian.
In "Toffee", this Millhorse dies when Star casts the Whispering Spell again to destroy the wand crystal in Ludo's hand.
Near the end of "Toffee", Star used the last remaining piece of magic in the universe that has not been corrupted by Toffee to give birth to a third Millhorse. Much younger than the previous two, this Millhorse has a white coat, a dark blue mane, a yellow horn, and a gold butterfly-shaped mark on its haunches.
- ↑ Star and Marco's Guide to Mastering Every Dimension by Dominic Bisignano and Amber Benson. March 7, 2017. Published by Disney Press. Page(s) 191. ISBN: 978-1484774199.