| Honorific Prefix: | Saint |
| Trésain | |
| Titles: | Curate of Mareuil on the Marne |
| Birth Date: | 6th century |
| Birth Place: | Ireland |
| Death Date: | 6th century |
| Death Place: | Mareuil on the Marne |
| Venerated In: | Reims area |
| Feast Day: | 7 February |
Saint Trésain (in French pronounced as /tʁe.zɛ̃/; or Tressan, Tresanus; 6th century) was an Irish missionary in France.His feast day is 7 February.
Saint Trésain is patron of Mareuil sur Marne (Mareuil-sur-Ay) and of the parish church of Avenay-Val-d'Or.
The monks of St Augustine's Abbey, Ramsgate wrote in their Book of Saints (1921),
The hagiographer Alban Butler (1710–1773) wrote in his Lives of the Fathers, Martyrs, and Other Principal Saints under February 7,
Laurent Majoret published his Vie de S. Tresain in Toul in 1650, reissued in Rheims in 1700 and in 1743.He wrote that Trésain was born in Ireland of honest and prosperous parents and decided to dedicate himself to God.He had six brothers, the saints Gibrain, Tésan, Germain, Véran, Atran and Pétran, and three sisters, the saints Trantle, Pomprie and Possenne, all of whom accompanied him to France.There he placed himself under Saint Remy, Archbishop of Reims, who directed them to stay at a place beside the River Marne. Wanting to become a priest, Trésain undertook the study of Latin and Christian works.After completing his study he was ordained by Remy at Reims, despite opposition from the gentry of Ay.He was assigned to the village of Mareuil sur Marne.He performed various miracles during his ministry.He died on 7 February and his body was taken to the abbey of Avenay.