Petrus is a Latin name derived from the Greek meaning "rock", and is the common English prefix "petro-" used to describe rock-based substances, like petros-oleum or "rock oil." As the source of Peter, it is a common name for people from antiquity through the medieval era, and may refer to one of the following:
As a name:
- Petrus, Saint Peter, the first pope
- Priest Petrus, 5th century Illyrian priest
- Petrus Abailardus, Latin name for Peter Abelard
- Petrus Alfonsus, Spanish Jewish writer
- Petrus Augustus, curopalates
- Petrus Aureolus
- Petrus Baldus de Ubaldis
- Petrus Bernardinus, Florentine sectarian
- Petrus Canisius, 16th century German Catholic theologian and polemicist
- Petrus Capuanus or Peter of Capua, an Italian scholastic
- Petrus Christus, (ca. 1410/1420 - ca. 1475/76), Dutch painter
- Petrus de Abano or Pietro d'Abano (1257 – 1315) Italian philosopher and doctor
- Petrus de Amalfia, 14th century Italian music theorist
- Petrus de Cruce, late 13th century composer and author, one of the most significant and influential composers of the late ars antiqua
- Petrus de Natalibus, Venetian hagiographer
- Petrus de Picardia, 13th century French music theorist
- Petrus de Sancto Dionysio, 14th century French music theorist
- Petrus Diaconus, several people
- Petrus frater dictus Palma ociosa, 14th century French music theorist, one of the first to illustrate current musical innovations
- Petrus Jacobus Joubert
- Petrus Le Viser, late 13th century musician, important in the history of tempo and rhythm
- Petrus optimus notator, 13th century musical scribe in Paris, important for notating Notre Dame polyphony
- Petrus Peregrinus = Peter de Maricourt, 13th century French writer on magnetism and astrolabes
- Petrus Ramus
- Petrus Trothun Aurelianis, 13th century singer of the Notre Dame School
Other:
- Petrus (genus), a genus of ray-finned fish
- Lars Petrus, speedcuber and inventor of the Petrus method
- Château Pétrus, a Pomerol Bordeaux wine producer
- Ubi Petrus, Ibi Ecclesia is a popular Roman Catholic motto.
- Tu es Petrus is a music piece of Franz Liszt.
- PETRUS, a short film by Andy Berlin.