Modestus was a Roman cognomen. It may refer to:

• Julius Modestus (1st century BC), Roman freedman and grammarian
• Marcus Mettius Modestus (procurator) (1st century AD), Roman governor of Egypt
• Aufidius Modestus (1st century AD), Roman philologist, commentator on Horace
• Mettius Modestus, Roman consul AD 82
• Gaius Trebonius Proculus Mettius Modestus (2nd century), Roman senator
• Modestus (apologete) (2nd century), Christian apologist who wrote against Marcion
• Quintus Aiacius Modestus Crescentianus, consul alongside Marcus Pomponius Maecius Probus in 228
• Saint Modestus, legendary saint and educator of Saint Vitus, martyr under Diocletian (c. 304)
• Modestus, martyr at Agde alongside Saint Tiberius during the Diocletianic persecution
• Domitius Modestus (fl. 358–377), Roman politician
• Gaius Sollius Modestus Sidonius Apollinaris (5th century), Roman poet and diplomat
• Modestus (bishop of Trier) (died 489), saint
• Modestus of Jerusalem (died 630), Christian patriarch of Jerusalem
• Modestus (Apostle of Carantania) (8th century), Irish missionary to the Carantanians and saint
• Modestus or Pseudo-Modestus (9th century?), supposed author of the Libellus de vocabulis rei militaris
• Modestus Yao Z. Ahiable (b. 1948), Ghanaian politician
• Modestus Kilufi (b. 1959), Tanzanian politician
• Modestus Setiawan (b. 1982), Indonesian footballer

• Modest (disambiguation)