Legio XXX Ulpia Victrix was a Roman legion levied by the emperor Trajan in 105 AD for the Dacian wars. The legion was active until disbandment of the Rhine frontier in the beginning of the 5th century. Their emblems were the gods Neptune and Jupiter and the Capricorn. "Ulpia" is derived from Trajan's family name Ulpius and the title "Victrix" means "victorious".

The legion's first base camp was in the province of Dacia in the Danube fronier, although it's likely that at least some of its legionaries took part in the Parthian campaigns of Trajan. In 122 they were moved to Xanten in Germania Inferior, where they remained for the following centuries. Their main tasks were public construction and police affairs.

In the 2nd century and the beginning of the 3rd century, units of the XXX Ulpia Victrix were allocated in Parthia, as well as Gaul, Mauretania and other Roman provinces, due to the peaceful situation in Germania Inferior.

In the civil war of 193, XXX Ulpia Victrix supported Lucius Septimius Severus, who granted them the title of Pia Fidelis ("faithful and loyal").

See also: List of Roman legions