Emperor Xian of Han
Cao Cao died on 15 March 220. His son and successor, Cao Pi, soon forced Emperor Xian to abdicate the throne in favour of himself, ending the Han dynasty. Cao Pi established a new state known as Cao Wei (sometimes known inaccurately as the Kingdom of Wei), and he granted Emperor Xian a noble title – Duke of Shanyang (山陽公). The former Emperor Xian died in 234 and was buried with honours befitting an emperor, using Han ceremonies, and the then emperor of Wei, Cao Rui, was one of the mourners. As Emperor Xian's crown prince was already dead, his grandson Liu Kang (劉康) inherited his dukedom, which lasted for 75 more years and two more dukes, Liu Jin (劉瑾) and Liu Qiu (劉秋), until the line was exterminated by invading Xiongnu tribes in about 309, during the Jin dynasty. This practice of an emperor conferring hereditary nobility on his predecessor, from whom he usurped the throne, was known as "er wang san ke" (二王三恪).
Emperor Ping of Han
Emperor Ping (9 BC – 3 February 6 CE) was an emperor of the Chinese Han Dynasty from 1 BC to AD 5. After Emperor Ai died childless, the throne was passed to his cousin Emperor Ping—then a child of eight years old. Wang Mang was appointed regent by the Grand Empress Dowager Wang. Dissatisfied with his father's dictatorial regency, in AD 3, Wang's son Wang Yu (王宇) conspired with Emperor Ping's maternal uncles of the Wei clan against Wang, but after they were discovered, Wang had not only Wang Yu and the Weis (except Consort Wei) put to death, but also used this opportunity to accuse many actual or potential political enemies as being part of the conspiracy and to execute or exile them. From here onwards, the Han Dynasty existed only in name. Furthermore, Wang Mang also designated his daughter as the empress consort to Emperor Ping to codify his legitimacy to power. Emperor Ping was allegedly poisoned by Wang Mang after reigning less than six years, because Wang was concerned that he would avenge his uncles, and his successor, the infant Emperor Ruzi, would be chosen by none other than Wang Mang himself.