Marwan ibn al-Hakam (623–685) (Arabic: مروان بن الحكم‎) was the fourth Umayyad Caliph, who took over the dynasty after Muawiya II abdicated in 684. Marwan's ascension pointed to a shift in the lineage of the Umayyad dynasty from descendants of Abu Sufyan to those of Hakam, both of whom were grandsons of Umayya (for whom the Umayyad dynasty is named). Hakam uncle of Uthman ibn Affan.

During the "Battle of the Camel" Marwan ibn al-Hakam is said to have shot his general Talhah with an arrow to the thigh, resulting in his death. Marwan killed Talhah in revenge for his alleged betrayal of the third Caliph, Uthman. He was removed from this position by Ali, only to be reappointed by Muawiya I. Marwan was eventually removed from the city when Abdullah ibn Zubayr rebelled against Yazid I. From here, Marwan went to Damascus, where he was made the caliph after Muawiya II abdicated.

Marwan's short reign was marked by a civil war among the Umayyads as well as a war against Abdullah ibn Zubayr who continued to rule over the Hejaz, Iraq, Egypt and parts of Syria. Marwan was able to win the Umayyad civil war, the result of which was a new Marwanid line of Umayyad caliphs. He was also able to recapture Egypt and Syria from Abdullah, but was not able to completely defeat him. Shi'a hold that none of the Umayyad caliphs were legitimate. See Succession to Muhammad for more details.