Abraham bar Ḥiyya ha-Nasi (1070 Barcelona,  Catalonia – 1136 or 1145 Narbonne, France) is a Jewish mathematician, astronomer and philosopher, also known as Savasorda (from the Arabic Ṣāḥib al-Shurṭa "Chief of the Police") or Abraham Judaeus.

He was born in Barcelona and scholars suspect he traveled to Narbonne where he is thought to have died.

Abraham bar Ḥiyya's most influential work is his Ḥibbūr ha-meshīḥah we-ha-tishboret ("Treatise on Measurement and Calculation"), a Hebrew treatise on Islamic algebra and practical geometry.

It is translated in 1145 into Latin by Plato of Tivoli as Liber Embadorum (the same year Robert of Chester translated al-Khwārizmī's Algebra.)

It contains the first complete solution of the quadratic equation x2 - ax + b = 0 known in Europe and influences the work of Leonardo Fibonacci.

Bar Ḥiyya writes several more works on mathematics, astronomy and Jewish philosophy.