Gnaeus Caecilius Simplex was a Roman senator, who was active during the middle of the first century AD. The ephemeral emperor Vitellius appointed him consul during the Year of Four Emperors with Gaius Quinctius Atticus as his colleague, replacing Martius Macer and Quinctius Atticus. Many believed Simplex had bribed Vitellius to be appointed to this magistracy, and he was accused of this in the Senate; however Vitellius defended Simplex, and "afterwards bestowed on Simplex a consulship that had not been bought with crime or money."