Aeimnestus (Gr. Ἀείμνηστος) is an Ancient Greek word, also spelled aeímnēstos and arímnēstos that means "unforgettable", literally "of everlasting memory". It was the name of multiple revered Greek warriors. A Spartan soldier Aeimnestus killed the Persian general Mardonius by hurling a boulder onto Mardonius' head during the Battle of Plataea in 479 BC. The event was described in Book 9 of the Histories of Herodotus. Plutarch calls the same man "Arimnestus" (Ἀρίμνηστος). A Plataean general Arimnestus led his city's host in the battles of Marathon and Plataea.