Quintus Petilius Cerialis Caesius Rufus (born around 30 AD) was a Roman general of the 1st century.

His name suggests that he was an adopted son of a Caesius family into the Petilii. His elder brother may have been Caesius Nasica. Cerialis was married to Flavia, oldest sister of Vespasian.

His first important assignment was as legate of the Roman legion IX Hispana in the Roman province of Britain, under governor Gaius Suetonius Paulinus. He took part in the defeat of the 60/61 rebellion led by Queen Boudicca of the Iceni, although he suffered a serious defeat when attempting to relieve the city of Camulodunum (Colchester), which was destroyed by the Britons. As a relative of Vespasian, Vitellius made him an hostage during 69 AD, in the crisis of the four emperors. Cerialis managed to escape and was one of the cavalry leaders that conquered Rome to the aproaching Vespasian. This success and his brother in law's trust gave him the command of Legio XIV Gemina, then stationed in the difficult province of Germania Inferior, in. Again, Cerialis had to deal with a local revolt, known as the Batavian rebellion, in which the local tribes, led by Civilis, a romanized prince, besieged two Roman legions at Xanten. Cerialis was again successful and received honours from emperor Vespasian. In 71 Cerialis was appointed governor of Britain, with Gnaeus Julius Agricola as second in command. As governor, Cerialis campaigned against the Brigantes of Northern England. In 74, Cerialis left Britain and returned to Rome as suffect consul. In 83 he was nominated consul for the second time, as a junior partner of the Emperor Domitian.

Tacitus says that he was a bold soldier rather than a careful general, and preferred to stake everything on the issue of a single engagement. He possessed natural eloquence of a kind that readily appealed to his soldiers. His loyalty to his superiors was unshakable.