He is Imam al-Haramayn Dhia' ul-Din Abd al-Malik ibn Yusuf al-Juwayni al-Shafi'i born in 17 February 1028 / 419 AH and said to have died on 19 August 1085 / 478 AH. He was a Persian Sunni Shafi'i jurist and mutakallim theologian. His name is commonly abbreviated as Al-Juwayni; he is also commonly referred to as Imam al Haramayn, meaning "leading master of the two holy cities", that is, Mecca and Medina. Al-Juwayni was born in a village on the outskirts of Naysabur called Bushtaniqan in modern day Iran. Al-Juwayni was a prominent Muslim scholar known for his gifted intellect in Islamic legal matters. Al-Juwayni was born into a family of legal study. His father, Abu Muhammad 'Abdallah b. Yusuf al-Juwayni, was a well-known master of Law in the Shafiâ²i community as well as a Shafi'i teacher and his older brother, Abu al-Hassan 'Ali al-Juwayni, was a Sufi teacher of Hadith.
Al-Juwayni grew up in Naysabur, an intellectually thriving area drawing scholars to it. Naturally, Juwayni did not have to search far for his education. At the time, the teachings of the Shafi'i school were closely linked to the Ash'ari theology which al-Juwayni decided to study for several years after the death of his father. He took over for his father at this point and began his teaching career at only 19 years of age. The Seljuks, at the time, were moving quickly in their conquest of eastern Iran and Tughril Beg became the first sultan. Tughril Beg was a Mutazili-Hanafi adherent and at the time, the Ash'arite theological camp and the Hanafi school of legal thought shared a hostile relationship based in differences of opinion regarding doctrine and when Tughril Beg was named wazir in Nishapur, he forbid al-Juwayni to practice or teach the Ash'ari theological perspective.
Al-Juwayni travelled to Mecca and Medina in search of an interim home. He taught and studied there in Hijaz for four years. During this time, al-Juwayni became hugely popularised. He gained a large following and was invited back to Nishapur by the founder of the Shafi'i Madrasa, Khwaja Nizam al-Mulk. Upon his return, Juwayni was appointed to teach the doctrine of the Ash'ari school at the Nizamiyya Madrasa until he died in 1085CE. Al-Juwayni spent his life studying and producing influential treatises in Muslim government; it is suspected that most of his works came out of this period after his return from Mecca and Medina.
Al-Juwayni was the teacher of one of the most influential scholars in the Islamic tradition, namely Imam al-Ghazzali. It was said that he said al-Ghazzali was his greatest achievement and also his diminished status for having produced to great of a pupil.