King Zhaoxiang of Qin
Because King Zhaoxiang had not yet legally come of age (traditionally at the age of 20), his mother, who was now known as Queen Dowager Xuan, became the regent. She was supported by her brothers, Wei Ran and Mi Rong (羋戎), as well as two other sons, Prince Yi (公子悝) and Prince Fu (公子巿), the four of them collectively known as the "Four Nobles" (四貴).
Lü Buwei
The "Shiji" mentioned that Lü Buwei had a beautiful "dancing girl", Lady Zhao, in his household, with whom Zichu became so infatuated that he asked for her. Lü Buwei reluctantly presented Lady Zhao to Zichu, and they returned to Handan. In 259 BC, Lady Zhao gave birth to a son, Ying Zheng, who eventually unified China under the Qin Dynasty and became historically known as "Qin Shi Huang" (First Emperor of Qin). After the death of King Zhaoxiang in 251 BC, Lord Anguo was enthroned and became historically known as "King Xiaowen", but he died three days after his coronation in 250 BC. Zichu succeeded his father and became historically known as "King Zhuangxiang". King Zhuangxiang appointed Lü Buwei as his chancellor (相國; or prime minister) and enfeoffed him as "Marquis Wenxin" (文信侯) with a taxable fief covering 100,000 households in Luoyang. While in office, Lü Buwei oversaw Qin's military campaigns against neighbouring states. When King Zhuangxiang died in 247 BC, Ying Zheng (then 13 years old) succeeded him, while Lü Buwei continued serving as a chancellor and regent to the young king.