the chief minister of the usurper Magnentius, first appears in history as Praefectus Orientis, in A. D. 340, and is probably the Marcellinus who stands in the Fasti as consul the following year. He was Comes Sacrarum Largitionum under Constans, and the most active promoter, if not the first contriver of the conspiracy by which that prince was destroyed (A. D. 350). Marcellinus, now holding the rank of Magister Officiorum and general in chief of the troops, was employed by the usurper to suppress the insurrection of Nepotianus, on which occasion he displayed the most savage cruelty towards the wealthier and more distinguished inhabitants of Rome. He subsequently headed the embassy despatched to offer terms of peace and alliance to Constantius, and is said to have been seized and detained by the indignant emperor, but we find him soon afterwards at liberty, commanding the armies of the West, and he probably perished at the great battle of Mursa, A. D. 351.

Marcellinus is represented by Julian as animated by the most violent and implacable hostility towards all the members of the house of Constantine, and as the master rather than the servant of Magnentius. [CONSTANS I.; CONSTANTIUS; MAGNENTIUS; VETRANIO; NEPOTIANUS.] (Codex Theod. Chron. p. 41; Julian, Orat. 1.2; Zosim. 2.41-54; Aurel. Vict. Epit. 41.)