Michael V "the Caulker" or Kalaphates (Greek: Μιχαήλ Ε΄ Καλαφάτης, Mikhaēl V Kalaphatēs), (1015 – August 24, 1042), was Byzantine emperor for 4 months in 1041–1042, as the nephew and successor of Michael IV and the adoptive son of his wife, the Empress Zoe.
Michael V was the son of Stephen by Maria, a sister of Emperor Michael IV. His father had been a caulker (hence the son's nickname), before becoming an admiral under Michael IV and botching an expedition to Sicily. Although the emperor preferred another of his nephews, the future Michael V was advanced as heir to the throne by his other uncle John the Eunuch and the Empress Zoe. Shortly before his death, Michael IV granted Michael V the title of Kaisar (Caesar), and, together with Zoe, adopted his nephew as son. On December 10, 1041, Michael V succeeded to the throne.
Determined to rule on his own, Michael V came into conflict with his uncle John the Eunuch, whom he almost immediately banished to a monastery. Michael now reversed his uncle's decisions, and recalled the nobles and courtiers who had been exiled during the previous reign, including the future patriarch Michael Keroularios and the general George Maniakes. Maniakes was promptly sent back to Southern Italy in order to contain the advance of the Normans.
On the night of April 18 to April 19, 1042 Michael V also banished his adoptive mother and co-ruler Zoe as well, becoming the sole Emperor. His announcement of the event in the morning led to a popular revolt; the palace was surrounded by the mob, which demanded Zoe's immediate restoration. The demand was met, and Zoe was brought back as join-ruler with her sister Theodora. On April 20, 1042 Theodora declared the emperor deposed, and he fled to seek safety in the monastery of the Stoudion together with his remaining uncle. Although he had taken monastic vows, Michael was arrested, blinded, and castrated. He died as a monk on August 24, 1042. In addition to his treatment of Zoe, his unpopularity seems largely due to his attempts at administrative reform, which were strongly resented by the dominant classes, whilst the lower classes considered him a common usurper.