|Lucius Petrus Dextrus|
|Place of origin:||Earth|
|Appearance:||The Fires of Pompeii|
|Main actor:||Phil Davis|
Lucius visited the Caecilius family the day before the eruption of Mount Vesuvius to get part of a marble energy converter designed by the Pyroviles from Lucius Caecilius Iucundus. Under the direction of the Pyroviles, he collected the pieces to build the converter inside the heart of Mount Vesuvius. It would convert the population of the world into more Pyroviles.
The Tenth Doctor and Caecilius' son Quintus found out he had breathed in the dust of Mount Vesuvius, actually the remains of the Pyroviles. This was slowly turning him into stone. The Doctor broke his arm off and escaped with Quintus. Later the High Priestess ordered him to advance the prophecy. He presented the energy converter to the Pyroviles in Mt. Vesuvius. The Doctor and Donna caused the eruption of Mount Vesuvius, killing the Pyroviles and Lucius inside it, along with the converter and the rest of Pompeii.