Ṣāʿid al-Andalusī (Arabic: صاعِدُ الأندلسي); he was Abū al-Qāsim Ṣāʿid ibn Abū al-Walīd Aḥmad ibn Abd al-Raḥmān ibn Muḥammad ibn Ṣāʿid ibn ʿUthmān al-Taghlibi al-Qūrtūbi (صاعِدُ بنُ أحمدَ بن عبد الرحمن بن محمد بن صاعدٍ التَّغْلِبيُّ) (1029 – July 6, 1070 AD; 420 – 6 Shawwal, 462 AH); an Arab qadi of Toledo in Muslim Spain, who wrote on the history of science, philosophy and thought. He practised as a mathematical scientist with a special interest in astronomy, and compiled a famous biographic encyclopedia of science that quickly became popular in the empire and the Islamic East.