The Old Woman is a character featured in The Legend of Zelda. She is the owner of the Potion Shops that are found across Hyrule. However, in order for the Old Woman to open up shop, Link must first find the Old Man in a cave in northeastern Hyrule, where he gives Link the Letter and tells him to take it to the Old Woman. After Link takes this Letter to the Old Woman, she starts selling the Water of Life and the 2nd Potion.
The Old Woman can be also found in different locations across Hyrule other than the Potion Shop. In one location, she asks Link to pay her, and in exchange she gives him a hint. This system has two useful hints; the first involves the Old Woman telling Link the secret on how to get to the fifth Dungeon, The Lizard. She tells him to travel up, up, up the mountain. This is a reference to how Link must travel north from the Lost Hills to reach the dungeon.
Old Woman Official Artwork from The Legend of Zelda
Old Woman Million Publishing Artwork from The Legend of Zelda
Old Woman Sprite from The Legend of Zelda