Impa did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Impa is the nursemaid to Princess Zelda and the last remaining person in the Sheikah tribe. She is seen throughout the Legend of Zelda series in different incarnations but she is best known as the Sheikah Bodygaurd. She is the Sage of the Shadow Temple, the Shadow Sage and is skilled at Martial Arts and Magic. She is a strong fighter and opened up Kakariko Village to the public.
Super Nintendo Band!
Impa is one of the eight Legend of Zelda characters available from the start in the musical cross series Nitendo Wii game Super Nintendo Band!.