The Qin dynasty’s Legalist prime minister was Li Si.
Li Si served as chancellor first under King Zheng of Qin, who became Qin Shi Huang, China’s First Emperor, and later under Qin Er Shi. He was a major architect of the centralized imperial government created after Qin conquered the other Warring States in 221 BCE. His policies emphasized uniform laws, administrative control, merit-based appointments, and the authority of the ruler.
Li Si also helped standardize weights and measures, coinage, carriage widths, and the writing system across the newly unified empire. He supported Legalist statecraft, although his political thinking drew on several earlier thinkers. A common mix-up is Shang Yang, who was an earlier Legalist reformer whose reforms strengthened Qin, but he was not Qin’s imperial chancellor at the time of unification. Han Fei was an influential Legalist philosopher, while Zhao Gao was a powerful court official who succeeded Li Si after his execution in 208 BCE.