Spartacus

Berserker of "Red" (“赤”のバーサーカー, "Aka" no Bāsākā) is the Berserker-class Servant of Deimlet Pentel of the Red Faction in the Great Holy Grail War of Fate/Apocrypha. Shirou Kotomine assumes command over him before he even meets his Master, but Berserker goes rogue before Shirou enacts his plan to officially become his Master.

~!He is instead forced to contract with Caster of Black when captured by the Black Faction.!~
~!Berserker's True Name is Spartacus (スパルタクス, Suparutakusu), the strongest Gladiator and the ringleader who raised a large-scale rebellion of slaves in Ancient Rome known as the War of Spartacus.!~