Mothax (Ancient Greek:μόθαξ,mothax, pl.: μόθακες,mothakes) is aDoric Greek word meaning "stepbrother".

The term was used for a sociopolitical class in ancientSparta, particularly during thePeloponnesian War (431–404 BC). The mothakes were primarily either offspring ofSpartiate fathers andhelot mothers or children of impoverished Spartiates. Mothakes were not able to contribute to thesyssitia, the core civic daily institution for citizens, and thus were not allowed to maintain an "equal" status. They were, however, permitted to fight as troops along withperioeci.

Though free, they were not Spartan citizens but were brought up alongside Spartan boys as their foster brothers. Due to the expenses of providing extra mess contributions, their rearing was usually sponsored by wealthy families. Some mothakes such asGylippus,Lysander andCallicratidas rose to prominence; the former's father exiled for treason and the latter raised in poverty.

• Hodkinson, Stephen.Property and Wealth in Classical Sparta (The Classical Press of Wales, 2000)ISBN 0-7156-3040-7
• Pomeroy, Sarah B., et al.Ancient Greece. New York, New York: Oxford UP, Inc, 1999. 483.