Tulak Hord, styled the Lord of Hate and Master of the Gathering Darkness, is an ancient Dark Lord of the Sith first mentioned in Star Wars: Knights of the Old Republic (2003) and appearing as a spirit in the Shadow of Revan expansion for Star Wars: The Old Republic. Neither his species nor his homeworld is established, and both fields are left blank here.
The character Kreia describes him as the greatest lightsaber duellist among the Sith Lords, which is the source of his entire reputation — he is famous largely because a well-written character said so. He conquered over a hundred worlds and was assassinated by his sole known apprentice, Ortan Cela. Star Wars Legends.
Catalogue entry. This figure has a verified record here rather than a full write-up — the encyclopedia labels its own depth instead of padding it.