Vajirananavarorasa (also spelled Wachirayan, Watchirayanawarorot, correct Pali spelling: Vajirañāṇavarorasa, Thai: วชิรญาณวโรรส, full title Somdet Phramahasamanachao Kromphraya Vajirananavarorasa สมเด็จพระมหาสมณเจ้ากรมพระยาวชิรญาณวโรรส ) (12 April 1860, Bangkok, Thailand - 2 August 1921, Bangkok, Thailand) was the tenth Supreme Patriarch of Thailand from 1910 to 1921. He helped to institutionalize Thai Buddhism.