Wikipedia article of the day is Yazid I. Check it out:
Article-Link Summary: Yazid I (c. 646 – 683) was the second caliph of the Umayyad Caliphate, ruling from April 680 until his death. His appointment, the first hereditary succession to the caliphate in Islamic history, was opposed by several Muslim grandees from Medina, including Muhammad’s grandson Husayn ibn Ali. Husayn refused to recognize Yazid following his accession and left for Kufa in Iraq to lead a revolt, but was killed in the Battle of Karbala. To suppress the subsequent rebellion in Arabia, Yazid sent an army that captured and sacked Medina. Next, Mecca was besieged for several weeks until the army withdrew as a result of Yazid’s death. The caliphate fell into a decade-long civil war known as the Second Fitna, ending with the establishment of the Marwanid dynasty. Yazid is considered an illegitimate ruler and a tyrant by many Muslims. Modern historians consider him a capable ruler, albeit less successful than his father Mu’awiya I, whose style of governance he continued.