One of the servants of Fate/Stay Night, Rider is a vigilant servant who is very loyal to her master, Mato Shinji, despite being unable to provide her with mana like the other Masters. Her true identity is Medusa, the Gorgon from greek Mythology, although she does not posses Medusa’s trademark "snake-like" hair. She does, however, have very long hair and blindfolds herself to keep her Mystic Eyes, Cybele, from petrifying anyone within her range of vision.
Luty sent me this cosplay after I said I needed to find other cosplays of other character from the series, Fate/Stay Night. Thanks for sharing!