Tom Ksaver - Eldian researcher and Warrior who held the power of the Beast Titan.  Served as Zeke Yeager's mentor and friend, since Zeke's own parents were lacking, especially Grisha.  He used his Titan for research, claiming it wasn't useful in war, and developed a close bond with Zeke, playing catch with him and influencing him to betray his parents. Ksaver expressed deep regret for his life and sins, wishing he had never been born. Tom is kind and fatherly.