Named in the Roman Canon
Marcellinus and Peter are named together as martyrs in whose fellowship we ask to share in Eucharistic Prayer 1 (The Roman Canon). Peter was an exorcist and Marcellinus a priest and both were martyred in Rome under Diocletian. There is also a church and catacombs in their honour on the Via Labicana in Rome, not far from St John Lateran's Basilica.

Story of their martyrdom
Peter had been imprisoned by the judge Serenus for confessing the Christian faith. Artemius the prison-keeper had a daughter Paulina who was troubled by an evil spirit.  Peter being a person entrusted by the Church with authority to cast out spirits was able to heal her.  On seeing this, Artemius, his wife and neighbours were all converted  to Jesus Christ. Peter then brought them to Marcellinus the priest, who baptized them.

When the judge Serenus heard of this, he summoned Peter and Marcellinus before him, rebuked and threatened them, demanding that they deny Christ. When they answered with Christian boldness, they were executed and their bodies abandoned in a place called the Black Wood so that other Christians would not be able to bury and venerate their bodies.

Burial and veneration
However, two Christian ladies, Lucilla and Firmina, came to know of this; they took the bodies and buried them with honour in a crypt near St Tiburtius, who was martyred some years earlier. The emperor Constantine is said to have built a church in their honour on the place and later had his mother St Helena buried there. The place where their bodies were found was afterwards called the White Wood.

Pope St. Damasus I (366-384), wrote that when he was a boy, he actually spoke with their executioner about them. He composed an epitaph in verse for their tomb: it states that through their martyrdom God gives us proof of his constant presence to his Church. A fragment of it survives in a nearby church.

The fact that Marcellinus and Peter are mentioned in the Roman Canon indicates that they were held in high honour from soon after their death.

Translation of their relics to Germany
In the early ninth century, Eginhard, secretary to and biographer of Charlemagne, became a monk in later life. In 827 he asked Pope Gregory IV to send him some relics of martyrs to enrich the monasteries which he had founded or repaired. The Pope sent him the bodies of Saints Marcellinus and Peter. These Eginhard located at Seligenstadt near Frankfurt, where, in 829, he built a church and monastery in their honour.

In art
In art both Marcellinus and Peter are depicted together, in priestly garments, and bearing palms. In the early 17th century, the archaeologist Antonio Bosio (called the "Columbus of the Catacombs")  claimed in his book Roma Sotterranea describes an ancient fragment representing Peter, Marcellinus, and Paulina standing together.

Cardinal priest of church
The Slovenian-born Archbishop of Toronto, Cardinal Aloysius Matthew Ambrozic, is the present cardinal priest of the Church of Saints Marcellinus and Peter in Rome.