Tobirama Senju

The Second Hokage is the younger brother to the First Hokage and Tsunade's great-uncle. As the brother of the First, the Second Hokage was a member of the Senju Clan of the forest. The First and Second together fostered Konohagakure into a growing village. He was once the teacher of the Third Hokage. He was hailed for being the greatest master of water jutsu, being able to create water from nothing, allowing him to use any Suiton jutsu without requiring a source.

He is later revived from the dead by Orochimaru using Impure World Resurrection to fight the Third Hokage during the Destruction of Konoha arc. His soul is eventually sealed into the stomach of the Death God, along with his brother and Orochimaru's arms.
Along with his brother and Madara Uchiha, he was also one of the founders of the Hidden Leaf.