Abu Taher (died 1021), better known by his regnal name Shams Al-Dawla ("Sun Of The State"), was the Buyid ruler of Hamadan from 997 to 1021.

However, she gained the support of the Kurdish ruler Badr ibn Hasanwaih and Shams al-Dawla.

Around 1013, following the death of the Badr ibn Hasanwaih, Shams al-Dawla occupied part of the former ruler's territory.

Sometime in the later part of his reign, he tried to replace Majd al-Dawla as the ruler of Ray, but the Sayyida foiled his plans.

In 1015, Shams al-Dawla called upon the prominent Persian scholar Avicenna in order to treat him.