Diablo II: Malah
Malah is an elderly merchant and healer of Harrogath in Act V. She cares a lot about Anya, the young woman who will later become part of a quest.
Malah gives one of the best rewards in the game - permanent all resistance. You have to complete the Prison of Ice quest though to get this.
Heals - refills your Life, Mana, and Stamina for free.
Trade - sells Armor, Staves, Wands, Scepters, Tomes, Healing Potions, Potions, Keys, Scrolls.
Prison of Ice