Impa

From Zelda - Wiki on Neoseeker

Impa has appeared in the following games:

The Adventure of Link

Impa is the Royal Family's caretaker and the one who revealed to Link his true destiny upon seeing the Triforce on Link's hand. She instructed him to travel to six different places throughout Hyrule and eventually to the Great Palace in order to awaken Zelda and restore peace to Hyrule.

Ocarina of Time

Impa is a Sheikah warrior and the hero of Kakariko Village. She takes care of Princess Zelda, she teaches you Zelda's Lullaby, which is used many times in The Legend of Zelda: Ocarina of Time, to access Darunia's room in the goron village as well as Zora's Domain. She is also the Shadow sage, this is revealed directly after beating the Shadow Temple.

Oracle of Seasons & Oracle of Ages

In the Gameboy Color games Impa was the guardian of either Din or Nayru depending on the game. Although she doesn't help much in Oracle of Seasons, she gives you the Wooden Sword in Oracle of Ages. (Unless you used special passwords but that is a different story.)

Zelda's caretaker, Impa is the first to be possessed by Veran. She tricks Link into moving the Trifoce Barrier that was previously blocking her entrance into Nayru's grove. Once there, she leaves Impa's body and possesses Nayru. Impa remains in the game in a house near the area where the game started, and offers helpful advice in certain times throughout the game.