Thrasher's Tail
Thrasher's Tail is, as the name implies, the tail of Thrasher, the evil, named alligator that spawns in the Blighted Grove. It is a quest item, and currently has no other known use.
After the launch of the Mondain's Legacy expansion, the Tail functioned as a bundle of flax and could be used to make a rare cloth color, known as "Necromancer Gray." However, this was a bug related to the use of the same graphic for both items, and was fixed with Publish 37.