Ayatullah al-Uzma Sayyid Abul-Qasim al-Khui was born in Rajab 15, 1317 A.H. (November 19, 1899) at Khu’i in Iranian Azerbaijan. Around the age of 13, he moved to Iraq and took up residence in Najaf where he began studying Shia theology with the scholars of that city. He attained the rank of Ayatollah and was subsequently recognized as a Marja. He continued to live in Najaf, becoming a teacher for the remainder of his life, and oversaw the studies of scholars who would be qualified to issue fatwas based on Shia theology.
Due to his prominent position as a teacher and scholar in Najaf, he became an important leader of worldwide Shias. He became the most prominent Grand Ayatollah in 1971 after the death of Grand Ayatollah Muhsin al-Hakim.