In Greek mythology, the name Thersander /θɜːrˈsændər, θɜːrˈsɑːndər/ (Greek: Θέρσανδρος) refers to several distinct characters, the most prominent of whom is Thersander the son of Polynices.
In Homer's Iliad, Thersander was one of the Epigoni, who attacked the city of Thebes in retaliation for the deaths of their fathers, the Seven Against Thebes, who had attempted the same thing. He was the son of Polynices and Argea.
Thersander may have bribed Eriphyle with the robe of Harmonia so that she sent her son, Alcmaeon, to fight with him. His father did the same with Harmonia's necklace to convince her to send her husband with the original attackers. The attack of the Epigoni was successful, and Thersander became the king of Thebes. Thersander intended to fight for the Greeks during the Trojan War, but was killed by Telephus before the war began, while the Greeks had mistakenly stopped in Mysia. He was succeeded by his son Tisamenus, whose mother was Demonassa.