The gens Nasidia was an obscure plebeian family at Rome. The gens is best known from Quintus Nasidius, one of the admirals of Gnaeus Pompeius Magnus during the Civil War. Although none of the Nasidii are known to have held any of the higher offices of the Roman state, a number are known from inscriptions. A coin of this gens depicts the head of Pompeius and a trident on the obverse, and on the reverse a ship, with the inscription Q. Nasidius.