Anaedilus L. Thanátos

Backstory

Grew up in a rich family, used an experimental time turner of my making to live 2 lives as a "muggle" studying the non-magic world and its relation to this world. He then grew up to be a famed politician and earned an order of Merlin 2nd class for peace. Then he retired and became a magical scientist and found a mixed spell and potion that made him immortal and protected from all low-level magical attacks. He also found out a way to communicate to and back from the afterlife and give a temporary physical form to ghosts. He fought many wars including the battle of Hogwarts and the 1st and 2nd wizarding world war. He still lives at the age 114.