Eutropius, Cleonicus, and Basiliscus were martyrs who suffered at Amasea in Pontus (Asia Minor) during the persecution under the emperor Diocletian, traditionally dated to about the year 308. The brothers Eutropius and Cleonicus, together with Basiliscus, who is identified in the tradition as the nephew of the Great Martyr Theodore the Recruit, were companions of Theodore. They are commemorated together on March 3.
According to the synaxarion, after the martyrdom of Saint Theodore the three were imprisoned, and during their confinement their preaching brought a number of the pagan prisoners held with them to the Christian faith. They were then brought before the governor and interrogated concerning their belief. The earlier governor, named Publius, is said to have died during Theodore's torture; his successor, Asclepiodotus, is described as more severe than his predecessor and presided over the questioning and torture of the three.
The account relates that the martyrs firmly confessed Christ and were severely beaten. After Eutropius and Cleonicus were crucified at Amasea on March 3, Basiliscus was kept in prison and was put to death separately on May 22 at Komana.