仇士良
Cui Yin was born in 854, during the reign of Emperor Xuānzong. He was from the prominent Cui clan of Qinghe (清河, in modern Xingtai, Hebei), was from the "Wushui branch " of the prominent Cui clan of Qinghe. Cui Yin's father Cui Shenyou was a chancellor during Emperor Xuānzong's reign. Cui Yin had at least one older brother, Cui Changxia (). (According to the biography of the powerful eunuch Qiu Shiliang in the "New Book of Tang", Cui Yin developed a hatred for eunuchs early in his life due to Cui Shenyou's relating to him of an incident during the earlier reign of Emperor Xuānzong's nephew Emperor Wenzong, when Qiu tried to have Emperor Wenzong deposed.)