In Chinese history, a Taishang Huang or Taishang Huangdi is an honorific and institution of retired emperorship. The former emperor had, at least in name, abdicated in favor of someone else. Although technically no longer the reigning sovereign, there are instances where the retired emperor continued to exert considerable power, if not more than the reigning emperor.
Emperor Gaozu of Han had also bestowed the title Taishang Huangdi on his then-living father Liu Taigong. He bestowed it onto his father to express filial piety. It was also intended to preserve the social hierarchy between father and son, as the former was a commoner and the latter was a dynastic founder.
In 301, during the War of the Eight Princes, Sima Lun became the emperor by forcing his puppet Emperor Hui of Jin to become the Taishang Huang. The title had strictly served as an honorific before, but it had become a tool of political infighting over the course of this incident.
Another significant occurrence of development was in 399, when Lü Guang of Later Liang abdicated. Lü Guang was old and had become mortally ill, but he wished to secure the transition of imperial power to his designated heir (the eldest son from his main consort) in the presence of another son who was older and posed a threat to the legitimate succession. Even though Lü Guang failed in his efforts, this incident was the earliest example where imperial retirement served as a method to secure succession.
During the Northern and Southern dynasties, this institution was employed by non-Han regimes in the north as a strategy to cast away from the tradition of the horizontal succession in favor of the Han tradition of a male primogenitor pattern of succession. In contrast, due to their Han heritage, the southern regimes had no need to make use and never employed the institution as a means to stabilize successions.
In 617, Li Yuan (later Emperor Gaozu of Tang) bestowed the title Taishang Huang upon Emperor Yang of Sui in absentia. Here, Li Yuan used the honorific as a legitimating cover for his seizure of power, in which the newly-installed Yang You served as his puppet emperor. In 626 during the Xuanwu Gate Incident, Prince Li Shimin of Tang led his armed men in a coup for the throne. During the course of the coup, he succeeded in killing his rival brothers, Crown Prince Li Jiancheng and Prince Li Yuanji. Within three days, Emperor Gaozu created Li Shimin as his heir. On the ninth day of the eight month, Emperor Gaozu abdicated in favor for his son Li Shimin (who became Emperor Taizong). He remained as Taishang Huang until his death in 635. He would only appear for ceremonial functions at court. In 712, Emperor Ruizong of the Tang dynasty retired in favor for his son who became Emperor Xuanzong. In 756, during the An Lushan Rebellion, Emperor Xuanzong went into retirement while he was in Shu (present-day Sichuan). His son, who was leading a military campaign in the northeast of Gansu at the time, would ascend the throne as Emperor Suzong.
In modern Chinese history after 1949, Deng Xiaoping has been called Taishang Huang in a pejorative context because he wielded much of his power without assuming the titles normally taken on by China's paramount leader, and because he belonged to Mao Zedong's generation of leaders but wielded influence over leaders who were a generation below him. The term has also been applied to other Communist Party senior officials without formal titles who were seen as meddling in the affairs of their successors, such as Chen Yun and Jiang Zemin.
Instances of Chinese rulers who were granted the title Taishang Huang and/or Taishang Huangdi: