emiya kiritsugu
Saber's previous master, freelancer and infamously known as the Magus Killer.
Husband of Irisviel von Einzbern, father of Illyasviel von Einzbern and Emiya Shirou.
Is a servant and Counter Guardian under the Assassin designation in the Fate/Zero Accel event in Fate/Grand Order.
See also
- Type-Moon wiki (spoilers): http://typemoon.wikia.com/wiki/Emiya_Kiritsugu