In Greek mythology, Mecisteus (/məˈsɪsˌt(j)uːs/; Ancient Greek: Μηκιστεύς Mēkisteús) may refer to the following personages:

• Mecisteus, an Arcadian prince as one of the 50 sons of the impious King Lycaon either by the naiad Cyllene,^[1] Nonacris^[2] or by unknown woman. He and his brothers were the most nefarious and carefree of all people. To test them, Zeus visited them in the form of a peasant. These brothers mixed the entrails of a child into the god's meal, whereupon the enraged Zeus threw the meal over the table. Mecisteus was killed, along with his brothers and their father, by a lightning bolt of the god.^[3]
• Mecisteus, one of the Seven Against Thebes who attacked the city. He was the son of Talaus and Lysimache.^[4]
• Mecisteus, an Achaean warrior who participated in the Trojan War. He was the son of Echius,^[5] another Greek soldier during the siege of Troy. Together with the Pylian Alastor, Mecisteus carried the wounded Teucer off the battle-field,^[6] as they later did with Hypsenor.^[7] Ultimately, Mecisteus was killed by the Trojan Polydamas.^[8]
• Mecisteus, one of the Suitors of Penelope who came from Dulichium along with other 56 wooers.^[9] He, with the other suitors, was killed by Odysseus with the help of Eumaeus, Philoetius, and Telemachus.^[10]