Abū Isḥāq Ibrāhīm ibn Yaḥyā al-Naqqāsh al-Zarqālī, also known as Al-Zarkali or Ibn Zarqala (1029–1087), was an Arab Muslim instrument maker, astrologer, and one of the leading astronomers of his time. Although his name is conventionally given as al-Zarqālī, it is probable that the correct form was al-Zarqālluh. In Latin he is referred to as Arzachel or Arsechieles, a modified form of Arzachel, meaning 'the engraver'. He lived in Toledo, Al-Andalus before moving to Córdoba later in his life. His works inspired a generation of Islamic astronomers in Al-Andalus.
The crater Arzachel on the Moon is named after him.
Al-Zarqālī was born in a village near the outskirts of Toledo, then the capital of the Taifa of Toledo.
He was trained as a metalsmith and due to his skills he was nicknamed Al-Nekkach "the engraver of metals". His Latinized name, 'Arzachel' is formed from the Arabic al-Zarqali al-Naqqash, meaning 'the engraver'.
He was particularly talented in Geometry and Astronomy. He is known to have taught and visited Córdoba on various occasions, and his extensive experience and knowledge eventually made him the foremost astronomer of his time. Al-Zarqālī was also an inventor, and his works helped to put Toledo at the intellectual center of Al-Andalus. He is also referred to in the works of Chaucer, as 'Arsechieles'.
In the year 1085 Toledo was taken by the Christian king of Castile Alfonso VI. Al-Zarqālī and his colleagues, such as Al‐Waqqashi (1017–1095) of Toledo, had to flee. It is unknown whether the aged Al-Zarqālī fled to Cordoba or died in a Moorish refuge camp.