Longtail is a lean, pale brown tabby tom with black stripes and green eyes. He has a "V"-shaped nick in his left ear, and a long tail.

Longtail was a Thunderclan elder who lived under Firestar's leadership in the forest and lake territory's and previously served as a warrior under Bluestar and Firestar. He was born to Robinwing and Patchpelt as Longkit, and he was later apprenticed to Darkstripe as Longpaw. As a warrior, Longtail was one of Tigerclaw's  strongest supporters, and he challenged Firepaw when he first joined ThunderClan, but was defeated by the kittypet. After Tigerclaw's betrayal, Longtail refused to join him, slowly earning Fireheart's respect. After his apprentice, Swiftpaw, was killed by Tigerstar's dogs, Longtail further turned his back on him. He gained Ferncloud as an apprentice and later became a mentor to Sootfur. Longtail was blinded by a rabbit and forced to retire early, but remained valued by the Clan. Longtail formed a close bond with his fellow elders, Mousefur and Purdy, but was killed by a falling tree. He ascended to StarClan and reunited with Mousefur during the battle against dark forest. He was saddened when Mousefur was killed by a Dark Forest tom and killed him in turn.