Gillian

Gillian is a Diablo I NPC, and is found in front of a house just to the west of Ogden's Inn. She is not a merchant and does not give or reward any quests, and her only purpose in Diablo is to relate pointless and boring gossips about her sick mother.

In Hellfire she has a quest speech about the Cathedral Map, as part of the Grave Matters quest. It's not necessary to speak with her to complete the quest.