Zhou Zong (周宗), courtesy name Juntai (君太), was an official of the Chinese Five Dynasties and Ten Kingdoms period state Southern Tang. Zhou was a close associate of its founding emperor Emperor Liezu and thus was honored by Emperor Liezu (Xu Zhigao/Li Bian) and his son and successor Emperor Yuanzong (Xu Jingtong/Li Jing). His two daughters became successive empresses (known as Empress Zhou the Greater and Empress Zhou the Lesser) for Emperor Yuanzong's son and successor, Southern Tang's final emperor Li Yu (often known as Li Houzhu).
Zhou Zong's birth date is not clearly stated in history — although he was said to be in his 70s at the time of his death during the Later Zhou invasion against Southern Tang, which was launched in 956 and ended in 958 in Southern Tang's submission to Later Zhou as a vassal — placing somewhat of a timeframe around the time of his birth. His family was from Guangling. In his youth late in the Tang Dynasty, there were great disturbances in the region. As a result, he lost his parents, and he was poor. During Wu (one of the successor states of Tang after Tang fell, which ruled over, inter alia, Zhou's home city of Guangling and had Guangling as its capital), Zhou came to serve under the general Xu Zhigao, an adoptive son of Xu Wen, Wu's regent, as Xu Zhigao's supply officer. Zhou was said to be particularly appropriate in protocols and wording, and served Xu Zhigao well, thus causing Xu Zhigao to greatly favor him.
When Xu Wen died in 927 at Jinling, Zhou was at Jinling. Xu Zhigao's younger brother (Xu Wen's then-oldest-surviving biological son) Xu Zhixun — who was then in a power struggle with Xu Zhigao over who would effectively succeed Xu Wen as Wu's paramount regent — told Zhou to inform Xu Zhigao, who was then in Guangling serving as junior regent over the regime of Wu's king (but who would soon thereafter declare himself emperor, following Xu Wen's final petition before death that he does so) Yang Pu, that there was no need for him to attend the funeral proceedings and that it was more important for him to pay attention to the affairs of the state. Zhou insisted that Xu Zhixun write this down in a letter, so Xu Zhixun did so. When Xu Wen's other biological sons were displeased that Xu Zhigao did not attend the funeral, Zhou showed the letter to them, and Xu Zhixun was unable to argue against what he himself had written.