Marcellinus may refer to:

• Marcellinus (consul 275), Roman imperial official
• Marcellinus (magister officiorum) (died 351), officer of Emperor Constans and of usurper Magnentius
• Marcellinus (magister militum) (died 468), a Roman general in the invasion of Africa against Geiseric
• Marcellinus (writer), author of a Life of Thucydides, 6th century
• Marcus Egnatius Marcellinus, a senator of Imperial Rome, Consul Suffectus in 116
• Marcellinus and Peter (died 304), two Christian martyrs
• Pope Marcellinus (died 304), third century pope
• Ammianus Marcellinus (c. 330–c. 400), Roman historian
• Narcissus, Argeus, and Marcellinus (died 320), martyrs at Tomi
• Marcellinus of Gaul (died 374), saint and evangelist
• Marcellinus of Carthage (died 413), saint and martyr
• Marcellinus Comes (Count Marcellinus, died 534), 6th-century chronicler

• Marcellinus Champagnat (1789–1840), priest and saint, founder of the Marist Brothers
• Marcellinus of Civezza (1822–1906), Italian Franciscan author

• Saint Marcellinus (disambiguation)