Ren Tohsaka

Ren Tohsaka was a member of the Tohsaka Family during the First Holy Grail War, and served as the second master of Saber during the war, the first being his father, Nagato Tohsaka, and the third being his younger sister, Nagisa Tohsaka. He was killed during a battle during the war, which is why he had to quickly give his Maste rights to Nagisa before he died.