In the Aengus Mac Nisse, St. Macanisius is listed as a patron Saint of Connor and Down and died 506-514. He was baptized as an infant by St. Patrick. The records consist chiefly of miracles, many of them fantastic and conflicting references. Irish literature is filled with stories of men such as Macanisius, supposed disciple of St. Patrick, who lived in isolation and prayer. He was a disciple of St. Olean.

After Macanisius made a pilgrimage to the  Holy Land and to Rome, upon his return to Ireland, St. Patrick consecrated him the first Abbot-Bishop and probable founder and hermit of Kells monastery, which became the Diocese of Connor, Ireland.

According to Latin life, he changed the course of a river Curi perhaps by natural means later regarded as miraculous for the convenience of his monks. He is also alleged to have saved the life of a child who was to become St. Colman of Kilruaidh. Colman's father was guilty of parricide and was sentenced to lose his own son.  St. Macanisius in vain interceded for his innocent life, so when the child was tossed into the air to be caught on the spear-points of the waiting tribesmen. Macanisius, standing on an adjacent hillock, prayed with such fervor that Colman's body was blown by the wind safely into his arms.

Among the more incredible legends about St. Macanisius, a story is told of him which may reveal his sense of reverence for the Holy Scriptures was so great that instead of carrying his gospel book in his satchel as was customary, he balanced the precious book on his back “hunched up or on all fours!”

An annual feast honoring St. Macanisius is held on September 3rd.