Zakariyya al-Ansari

Sheikhul Islam Abū Yaḥyā b. Muḥammad b. Zakariyyā, Zayn al-Dīn al-Sunaykī (Arabic: زكريا الأنصاري) also known as Zakariyyā al-Ansārī was an Egyptian Sunni polymath. He is considered the leading specialist in fiqh, usul al-fiqh, hadith, usul al-hadith, tafsir, ulum al-Qur'an (Qur'anic sciences), Qu'ranic recitation, grammar, linguistic, rhetoric, philology, history, literature, genealogy, kalam (Islamic theology), logic and Sufism. He also excelled in other sciences such as medicine, engineering, astronomy, and mathematics.

He is described as the most renowned and revered scholar, judge and teacher of his time. He is highly regarded for his profound knowledge in all of the sciences and his books of various subjects became a reference for later scholars. He is deemed to be the mujaddid of the 9th century Hijri. He is regarded as the mujtahid and foremost authority in the Shafi'i school. According to the Shafi'i tradition, the most famous usage for "Shaykh al-Islām" is with Zakariyya al-Ansari.