Ya'qub ibn al-Layth al-Saffar (????? ?? ????? ??????), or Ya'qub-i Layth-i Saffari (????? ??? ?????), born Radman pur-i Mahak (Persian: ?????? ??? ?????) (October 25, 840 – June 5, 879), a Persian coppersmith, was the founder of the Saffarid dynasty of Sistan, with its capital at Zaranj (a city now in south-western Afghanistan).
Under his military leadership he conquered much of the eastern portions of the Greater Iran consisting of modern-day Iran, Afghanistan, Turkmenistan, Uzbekistan, Tajikistan as well as portions of western Pakistan and a small part of Iraq.
He was succeeded by his brother, Amr ibn al-Layth.