Saint Mellonius (229-314) was an early 4th-century Bishop of Rotomagus (now Rouen) in the Roman province of Secunda Provincia Lugdunensis (now Normandy in France).

After a long episcopate, in 311, he retired to a hermit's cell at a place called Hericourt, where he died A.D.

[6] In the 2004 edition of the Roman Martyrology, Mellonius is listed under the same date, 22 October, with the Latin name Mallóni.

He is mentioned as follows: 'At Rothómagi (Rouen), bishop, who in that city announced the Christian faith and handed on the episcopate'.

[8] Mellonius was buried at Rouen, but his remains were subsequently translated to a church in Pontoise towards the end of the eighth century to protect them from Norse warbands.