Master Eraqus.

Master Eraqus is a Keyblade Master featured in Kingdom Hearts Birth By Sleep. He is the master of Terra and Aqua, and he also serves as the second master of Ventus.

In Majestic Guardian, He's a master of Terrence and uncle-like figure for him. He's member of the Majestic Guardian and the Council of Light.

During the course of the series, the Keyblade Master came to have a relation with Ishizu Ishtar.

In Lucemon Returns, he finally met his end along with Jiraiya when he and the Toad Sage took Lucemon's blast for Terrence and Brandon. 

His essence was absorbed along with Jiraiya's, but after Lucemon's defeat at the hands of the Majestic Dragon, both were free to move onto the next life.