The Medusa materialized in the Fifth Holy Grail War appears differently to her legend. She appears to be in her human form, unlike her legend where she has snake for her hairs, she has long purple hair.

She wears an eye cover that seals her excessively powerful Mystic Eyes of Petrification within the Bounded Field. Her sight is completely sealed. Although Rider perceives the world through senses such as hearing, touch, smell, and magic-detection, she is able to acquire more precise information than sight.[8]

She has a complex about her own height and the way she gets embarrassed when people see her Mystic Eyes, she might actually be pretty ladylike. Because of her outward appearance and primary weapon, a lot of people thought she was going to be an Assassin class Servant.

In her casual attire, she wears a black polo neck top and blue jeans. She wears Touko Aozaki's "Mystic Eye Killer" to disable her Mystic Eyes. It only seals the power of petrification. It does not act like the Breaker Gorgon, which "seals all magical properties".
Rider's True Name is Medusa (メドゥーサ, Medūsa?), the Gorgon from Greek mythology. Rather than being a regular Heroic Spirit, she is an existence closer to a Divine Spirit, but her actions have made it better to categorize her as an "anti-hero closer to a monster." With her older sisters Stheno and Euryale, they made up the three Gorgon Sisters who inhabited the Shapeless Isle. She was known as the "woman who dominates", an anti-hero who became as such due to the dark thoughts of humans. Differing from someone like Hassan-i-Sabbah who was a hero who actually existed, she is said to be one of legends born by the gathering of belief.

The legend of Medusa is different than her actual life. She was said to be a half-human, half-god female beast often portrayed with the form of a snake. Originally she was an Earth Goddess (大地の女神, Daichi no Megami?). While all originally beautiful women, she and her sisters were hated by Poseidon's wife because of his love for them. Athena, jealous of their beautiful hair, transformed them into demons. Secluding themselves in a lightless temple on the Shapeless Isle, they only attacked humans with a reason. Eventually, as a victim of the gods' unreasonable actions, she was to have her head cut off on their whim. Defeated by Perseus by reflecting her petrification back at her with his mirror-like shield, Pegasus, the son of Poseidon, was said to have sprung from the blood of her headless neck.