Quintus Petillius Cerialis Caesius Rufus, otherwise known as Quintus Petillius Cerialis, was a Roman general and administrator who served in Britain during Boudica's rebellion and went on to participate in the civil wars after the death of Nero. He later crushed the rebellion of Julius Civilis and returned to Britain as its governor.
Because he probably succeeded Caesius Nasica as commander of Legio IX Hispana, and since brothers are often attested as serving in succession in the same post, Anthony Birley suggests that Cerialis was the younger brother of Nasica, and had been adopted by Petillius Rufus, who was known as praetor in AD 28. However, in his monograph of naming practices in the first centuries of the Roman Empire, Olli Salomies argues that Cerialis was actually the biological son of Petillius Rufus by a woman named Caesia, who may have been the daughter of a Caesius Cerialis, therefore Caesius Nasica would not have been his brother "but a close relative."