Basil II Porphyrogenitus (Greek: Βασίλειος Πορφυρογέννητος, romanized: Basileios Porphyrogennētos; c. 958 – 15 December 1025), nicknamed the Bulgar Slayer (Greek: ὁ Βουλγαροκτόνος, romanized: ho Boulgaroktonos), was the senior Byzantine Emperor for almost 50 years (10 January 976 – 15 December 1025), having been a junior colleague to other emperors since 960. He and his brother Constantine were named as co-rulers before their father Romanos II died in 963. The throne went to two generals, Nikephoros Phokas (r. 963–969) then John Tzimiskes (r. 969–976), before Basil became senior emperor. His influential great-uncle Basil Lekapenos was the de facto ruler of the Byzantine Empire until 985. Basil II then held power for forty years.