Black Hand
From Tolkien Gateway

Sketch by J.R.R. Tolkien
The Black Hand was a title of Morgoth, used by Beleg to explain how Morgoth's power had expanded southwards Beleriand after the Nirnaeth Arnoediad.[1] In the Third Age, the epithet was applied twice to Sauron by Gollum, once explaining how Sauron had four fingers after Isildur cut off one.[2]