The gens Ulpia was a Roman family that rose to prominence during the first century AD. The gens is best known from the emperor Marcus Ulpius Trajanus, who reigned from AD 98 to 117. The Thirtieth Legion took its name, Ulpia, in his honor. The city of Serdica, modern day Sofia, was renamed as Ulpia Serdica.

Marcus Ulpius Traianus was a Roman senator and the father of Emperor Trajan.