Abu Bakr Muhammad ibn al-Walid ibn Khalaf al-Tartushi أبو بكر محمد بن الوليد بن خلف الطرطوشي (b. 451 A.H./1059 C.E. - d. 520 A.H/1127 C.E.) was a famous jurist originally from Tortosa طرطوشة, in Muslim Spain.
He travelled in pursuit of knowledge, as was the custom of his day, seeking to educated himself on various scholars in different part of the world, as far east as Baghdad, Damascus, Aleppo, Cairo, and Alexandria.
He settled in Alexandria, Egypt, teaching there in a school. He opposed the Ismaili tendency of the Fatimid dynasty in Egypt. He also, along with al-Gazzali, issued a fatwa for Yusuf Ibn Tashfin, the Almoravid ruler allowing him to invade Spain and depose the divided Taifa kingdoms.
One of his famous works was Siraj al-Muluk سراج الملوك. He also wrote other works.
He died in Alexandria, and his grave is still known to this day.
Abu Bakr should not be confused with Ibrahim ibn Yaqub al-Tartushi إبراهيم بن يعقوب الطرطوشي who was a Jewish merchant, slave trader, traveller and diplomat. He was sent by al-Hakam al-Mustansir, Emir of Cordoba to Otto of Magdeburg. He wrote a book about his travels, and died 390 A.H.