Frostfur

Spoiler warning: Plot and/or ending details follow.
Frostfur was a ThunderClan elder who had served as a warrior under Sunstar's, Bluestar's and Firestar's leaderships in the forest territories. She was born as Frostkit to Robinwing and Fuzzypelt along with her sister Brindlekit. As an apprentice, Frostpaw was mentored by Bluefur and later earned her warrior name, Frostfur. She gave birth to Lionheart's kits: Brackenfur, Cinderpelt, Thornclaw, and Brightheart. She retired to become an elder and chose to stay behind while the other Clans left on the Great Journey. She later ascended to StarClan.