Marcellinus may refer to:
- Pope Marcellinus, third century pope
- Ammianus Marcellinus, Roman historian
- Marcellinus (writer), author of the life of Thucydides
- Marcellinus (magister officiorum) (d. c. 351), officer of Emperor Constans and of usurper Magnentius
- Marcellinus of Gaul (d. 374), saint and evangelist
- Marcellinus of Carthage (d. 413), saint and martyr
- Marcellinus and Peter (d. 304), two Christian martyrs
- Marcellinus (magister militum) (d. c. 468) a Roman general who took part in the invasion of Africa against Geiseric, together with Heraclius and Basiliscus
- Marcellinus Comes (Count Marcellinus), 6th-century chronicler
- Narcissus, Argeus, and Marcellinus, martyrs at Tomi