Posidonius or Poseidonios may refer to:
- Poseidonios the Macedonian (3rd century BC?), a siege engineer mentioned by Biton of Pergamon
- Posidonius (1st century BC), Stoic polymath
- Posidonius (bishop of Urgell), bishop between AD 814 and 823
- Posidonius (crater), a lunar impact crater
This page was last edited on 13 August 2022, at 16:42