Marianus is a male name, formerly an Ancient Roman family name, derived from Marius. Marianus may refer to:
Blessed Marianus Scotus, abbot of St. Peter's at Ratisbon, born in Ireland before the middle of the eleventh century
Jozef Marianus Punt (born 1946), Roman Catholic bishop of Haarlem-Amsterdam in the Netherlands
Marianus Brockie, D.D. (1687–1755), Benedictine monk
Marianus II of Cagliari (died 1130), also known as Torchitorio II, Judge of Cagliari from c. 1102 to his death
Marianus of Florence (died 1523), Friar Minor, historian, and chronicler of the Franciscan Order; born in Florence about the middle of the fifteenth century
Marianus Scotus (1028–1088), Irish monk and chronicler, an Irishman by birth, and called Máel Brigte, or Devotee of St. Brigid
Marianus of Arborea
Marianus I of Arborea (died 1070), the Judge of Arborea from 1060 to his death
Marianus II of Arborea (died 1297), the Judge of Arborea from 1241 to his death
Marianus III of Arborea (died 1321), the sole Judge of Arborea from 1308 to his death
Marianus IV of Arborea (1329–1376), called the Great, the Judge of Arborea from 1347 to his death
Marianus V of Arborea (1378–1407), the Judge of Arborea from 1387 until his death
Marianus of Torres
Marianus I of Torres (died 1082), the Judge of Logudoro from 1073 until c. 1082
Marianus II of Torres (died 1233), the Judge of Logudoro from 1218 until his death
