Zaleucus (Ancient Greek: Ζάλευκος; fl. 7th century BC) was the Greek lawgiver of Epizephyrian Locri, in Italy, said to have devised the first written Greek law code, the Locrian Code.

Although the Locrian code distinctly favored the aristocracy, Zaleucus was famous for his conciliation of societal factions. No other facts of his life at all are certain. According to legends, he punished adultery with the forfeiture of sight. When his own son was condemned of this, he refused to exonerate him, instead submitting to the loss of one of his own eyes instead of exacting the full penalty of the culprit. Another law that he established forbade anyone from entering the Senate House armed. Faced with an emergency, he did so anyway, but when he was reminded of the law, he immediately fell upon his sword as a sacrifice to the sovereignty of the claims of social order. A similar story is told of Charondas.