William Soeryadjaya, a.k.a. Tjia Kian Liong (Chinese: 謝建隆; pinyin: Xiè Jiànlóng; December 20, 1922 – April 2, 2010), also known as Oom (Uncle) Willem, born in Majalengka, was a Chinese Indonesian businessman who co-founded Astra International, Indonesia's largest conglomerate.
He lost his parents at the age of 12 and had to cease his education at 19. But he continued his education in later years and studied at Leder & Schoenindustrie in the Netherlands.
Soeryadjaya co-founded Astra, then a trading company, in 1957. The company grew to become Indonesia's largest automobile retailer and the country's biggest company by market value. The company, which also owns finance, plantation, auto parts manufacturing, heavy machinery and mining services and automotive businesses, sells Honda motorcycles, BMW, Daihatsu, Peugeot, Citroen and Toyota vehicles throughout Indonesia. In March 2010, Astra overtook Telkom Indonesia to become Indonesia's most valuable company.
Soeryadjaya lost control of Astra in 1992, when he sold most of his family's shares in order to rescue his eldest son's (Edward Soeryadjaya) Summa Bank, which had suffered from a credit crisis and finally collapsed. He personally guaranteed all Summa Bank depositors their money back, and all depositors received their money back with interest without using any bailout package from the government at the expense of his ownership in Astra.
In 2009, Forbes magazine rated the Soeryadjaya family as Indonesia's 18th wealthiest family.
William Soeryadjaya died at Medistra Hospital in Jakarta on April 2, 2010, at the age of 87.