Impa is a recurring character in the Legend of Zelda series. Usually, she serves as the nursemaid or bodyguard to Princess Zelda. She appears in numerous games, including as an easter egg in the Wind Waker, in a stained-glass window in Hyrule Castle's basement.
Her appearance in games varies drastically, although she is usually depicted as an elderly woman, with one exception of in the Skyward Sword when she appears as a tall, slender woman (but, she is also realized to be the Old Woman at the Sealed Grounds in the present day at the end of the game, only having appeared in the past thus far). Another unique characteristic of Impa in the Skyward Sword is that she is quite skeptical of Link being the true Chosen Hero until midway through the game, when he assists in battling Ghirahim at the Gate of Time.
Some of Impa's other appearances include Legend of Zelda, Zelda II: Adventure of Link, Ocarina of Time, Oracle of Seasons, and Wand of Gamelon.