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
Lü Buwei (291–235 BC) was a politician of the Qin state in the Warring States period of ancient China. Originally an influential merchant from the Wey (衛) state, Lü Buwei met and befriended King Zhuangxiang of Qin, who was then a minor prince serving as a hostage in the Zhao state. Through bribes and machinations, Lü Buwei succeeded in helping King Zhuangxiang become the heir apparent to the Qin throne. In 249 BC, after King Zhuangxiang ascended the throne following the death of his father, King Xiaowen, he appointed Lü Buwei as his chancellor (相國) and ennobled him as "Marquis Wenxin" (文信侯). After King Zhuangxiang's death in 247 BC, Lü Buwei became the chancellor and regent to King Zhuangxiang's young son, Ying Zheng, who later became Qin Shi Huang (First Emperor of the Qin Dynasty).