Archagathus (Greek: Ἀρχάγαθος, fl. 4th century BC) was a Syracusan Greek Prince.
Archagathus was the son of Archagathus by an unnamed wife, being a paternal grandson of the Sicilian Greek King Agathocles of Syracuse from his first wife.
Archagathus was described as a youth of great bravery and daring. After the death of his father in 307 BC, Archagathus murdered his paternal uncle Agathocles, so that he would succeed his paternal grandfather. After the death of his paternal uncle, he was in turn murdered by a local Greek citizen called Maemon.