Tol-in-Gaurhoth

Tol-in-Gaurhoth or Isle of Werewolves was a fortress held by Sauron in the First Age, once called Tol Sirion. In the Lay of Leithian it was called Wizard's Isle.

Tol-in-Gaurhoth began as the Minas Tirith of Finrod Felagund, and was held by Orodreth for his uncle to guard the vale of Sirion. However, Orodreth was powerless to stop Sauron from taking the isle, and fled south. Sauron began breeding large wolves in the isle which he sent evil spirits in, turning them into werewolves.

Beren Erchamion on his quest for the Silmaril enlisted Finrod's aid, but they were captured passing the isle, and their companions slain one-by-one. Finrod saved Beren's life, but died himself.

Lúthien and the Hound Huan came to Beren's rescue, and while Huan killed the wolves Lúthien got control over the isle's magic from Sauron. The isle was destroyed and cleansed, and remained clean afterwards, and no new tower was erected there.