Umar ibn Sa'ad (or Amir ibn Sad) (Arabic: عمر بن سعد) (fl. 620–680) was the son of Sa'ad ibn Abi Waqqas. He was a clergyman and governor of Ray city, and took orders from Ibn Ziyad. He led the troops that murdered Husayn ibn Ali in the Battle of Karbala.
The historian Tabari has quoted Umar ibn Saad to have said to Ubaydullah ibn Ziyad, "By God, the sincerity I performed towards you with regard to killing Husayn was such that if I had performed such sincerity for my father, I would have fulfilled his rights."[1]