Io

Io is a character featured in Clash of the Titans, portrayed by Gemma Arterton

Background
Io  once  refused to be seduced by a god's advances, so he cursed her with agelessness and spent many of her time seeing her loved ones die.

She was later the sworn protector of Perseus and guided him to his family but was too late to save his mother, Danae.

Wrath of the Titans
By Wrath of the Titans, Io had passed away again due to presumably giving birth to hers and Perseus' son, Helius.

Family

 * Perseus (husband)
 * Helius (son)

Deceased

 * Zeus (father-in-law)
 * Danaë (mother-in-law)
 * Spyros (adoptive father-in-law)
 * Marmara (adoptive mother-in-law)
 * Tekla (adoptive sister-in-law) 

Powers and Abilities

 * Multilingual: Io can understand more than one language, as she understood Greek as well as the Djinn's language.
 * Healing: Io knows how to heal people
 * An unknown ability, but she led Perseus to his family with unknown abilities.

Former Abilities

 * Immortality (limited): She was cursed to never age, to be immortal by Poseidon. However, she could still be killed.

Trivia

 * Io is based on the mythological character of the same name and alludes to Princess Andromeda in Greek Mythology and the original 1981 Clash of the Titans.