The most unnerving thing about him is that while he is evidently a hollow shell of what was once a man, he can make you believe he has some form of humanity left.
—Jutta Viddo
Darth Mavet was the leader of a group of Sith Lords known as the Black Legion, who set out to destroy a militia group of Jedi Knights led by Mitakur. Mavet was a powerful Sith Lord and proclaimed leader of the Black Legion, gaining the title of "Lord of Poison" because of the unsettling effect he had on living organisms and plants that when his skin touched them, they would grow ill and vegetation withers and died around him.
Due to the mysterious nature of the Legion, neither his nor any other member's life was widely known to anyone, even each other. Mavet was known for his ruthless but very elegant form of fighting, not moving too much and having lightning-speed reflexes to defend himself from attacks. They did not help as much as they should have in his last battle with Mitakur, and was impaled in the face by his enemy's lightsaber during the Battle of Malicar III.