In Greek mythology, Medusa was the most beautiful and arguably the most well known of the three Gorgon sisters, as well as the only mortal of the three. (The other sisters being Euryale and Stheno.) Medusa was cursed by the goddess Athena after she desecrated one of Athena’s temples by sleeping with Poseidon inside. Gazing upon Medusa after Athena’s curse would turn anyone to stone. She was beheaded by the Greek hero Perseus, who then used her head as a weapon until giving it to the goddess Athena to place on her shield. Medusa, or characters inspired by her, have made many appearances in video games over the years.
Kid Icarus Series
Medusa is the primary antagonist of the original Kid Icarus and a major antagonist in Kid Icarus: Uprising. Unlike the Greek myth the character is inspired by, this incarnation of Medusa is the goddess of darkness, in contrast to Palutena, the goddess of light. In the original game, she was cursed by Palutena and banished to the underworld for turning humans to stone. Medusa retaliates by sending the forces of the underworld against Palutena, capturing her and members of her forces, including the protagonist Pit. Pit escapes his captivity and the underworld, collects the three sacred treasures, and defeats Medusa at the game's end, freeing Palutena.
In Kid Icarus: Uprising, Medusa returns seeking revenge against Palutena and Pit for their actions in the original game. She leads the Underworld Army once again and fights against the forces of light. Only when Pit and Palutena are able to recover the Three Sacred Treasures from the Space Pirates are they able to face her in battle. After her defeat, it is revealed that Hades is the one who was actually pulling the strings and the true force behind Medusa's revival. With Medusa defeated, he reveals himself and proceeds to gather souls to expand his army. She appears one last time at the end of the game, where she saves Pit and rebels against Hades, insisting that she will no longer be his pawn. After a brief struggle, Hades overpowers her, and she is defeated once again, but not before severely weakening Hades and giving Pit time to recover in order to deliver the final blow.
Medusa's appearance in Uprising is merely an illusion she conjures to hide her true face. She drops it when focusing on the fight with Pit in Chapter 9, revealing the true, monstrous appearance that she had been cursed with.
Medusa has appeared off and on in the Castlevania series in a few different forms. In the original Castlevania, Medusa was not present as a singular entity. Rather, Medusa heads fly across the screen as a standard enemy type, although there is a giant Medusa head, which appears as a boss in the game. This head is simply called, "Medusa" rather than "Medusa head". In other games such as Castlevania: Lament of Innocence, Medusa appears as a unique boss enemy.