Emperor Reizei (冷泉天皇; 12 June, 950 - 21 November, 1011) was the 63rd emperor of Japan (967 - 969). His name in birth was Prince Norihira (憲平親王).

Reizei was the second son of Emperor Murakami. His mother was a daughter of Fujiwara no Morosuke . Soon after his birth he was appointed to the crown prince of his father. This appontment was supposingly under the influence of Morosuke and his brother Fujiwara no Sanetomo who seized the power in the court.

He had a mental illness, his succession was therefore considered problematic. In 967 his father Murakami died and Reizei ascended to the throne at the age of eighteen and Sanetomo was appointed Kanpaku regend to support the emperor in his illness. A struggle happened between two princes of Murakami which of them would be apponted to the crown prince. In 969 Reizei retired and received the honorific title of Reizei-in Joko (Retired emperor in Reizei-In).