Thersander was a son of Polynices and Argia, and a king of Thebes. Another Thersander was a son of Sisyphus. The name means 'encourager of men', from tharsyno, 'to encourage' and anerandros, 'man'. An alternative interpretation might be 'warm men', from thermos, 'warm', 'hot', 'rash', 'hasty' and aner, andros.

This could be purely descriptive in an allusive sense, referring to busy activity such as commerce, or else to rashness of action. Either of these two shades of meaning could refer specifically to the son of Sisyphus, since Sisyphus himself was noted for his activity and enterprise, as well as his cunning.