The old Roman lists of the 5th century, which passed over into the Martyrologium Hieronymianum, contain the names of the two martyrs Nereus and Achilleus, whose grave was in the Catacomb of Domitilla on the Via Ardeatina.

Maii, Romae in coemeterio Praetextati natale Nerei et Achillei fratrum (On 12 May at Rome in the cemetery of Praetextatus [an evident error for Domitilla?]

[3] The Itineraries of the graves of the Roman martyrs, written in the 7th century, are unanimous in their indication of the resting-place of these saints (Giovanni Battista de Rossi, "Roma sotterranea", I, 180–83).

There was also found a large fragment of a marble slab, with an inscription composed by Pope Damasus, the text of which is well known from an ancient copy.

This oldest historical mention of Nereus and Achilleus[5] tells how the two as soldiers were obedient to the tyrant, but suddenly being converted to Christianity, joyfully resigned their commission and died the martyr's death.

According to these legends, Nereus and Achilleus were eunuchs and chamberlains of Flavia Domitilla, a niece of the Roman Emperor Domitian; with the Christian virgin, they had been banished to the island of Ponza (Pontia), and later on beheaded in Terracina.

Nereus and Achilleus were buried in a very ancient part of the Catacomb of Domitilla, built as far back as the beginning of the 2nd century; based on this, the Catholic Encyclopedia concludes that they are among the most ancient martyrs of the Roman Church, and stand in very near relation to the Flavian family, of which Domitilla, the foundress of the catacomb, was a member.