Gnaeus or Cnaeus was a Roman praenomen derived from Etruscan Cneve, of unknown meaning.
Some individuals named Gnaeus were:
- Gnaeus Calpurnius Piso
- Gnaeus Cornelius Cinna Magnus
- Gnaeus Cornelius Scipio Asina
- Gnaeus Cornelius Scipio Calvus
- Gnaeus Domitius Afer
- Gnaeus Domitius Ahenobarbus, general of the 1st century BC
- Gnaeus Domitius Ahenobarbus, relative of emperors of the 1st century AD
- Gnaeus Domitius Corbulo, general of the 1st century AD
- Gnaeus Egnatius, builder of Via Egnatia
- Gnaeus Julius Agricola
- Gnaeus Julius Verus
- Gnaeus Marcius Coriolanus
- Gnaeus Naevius
- Gnaeus Octavius
- Gnaeus Papirius Aelianus
- Gnaeus Papirius Carbo
- Gnaeus Pompeius
- Gnaeus Pompeius Magnus
- Gnaeus Pompeius Strabo
- Gnaeus Pompeius Trogus