The reign of the emperor Diocletian (284−305) marked the final widespread persecution of Christians in the Roman Empire.
The most intense period of violence came after Diocletian issued an edict in 303 more strictly enforcing adherence to the traditional religious practices of Rome in conjunction with the Imperial cult.
Martyr narratives flourished later as a genre of Christian literature, but are not contemporary with the persecutions and are often of dubious historicity.
This article lists both historical and legendary figures traditionally identified as martyrs during the reign of Diocletian.
Eusebius recorded many accounts of martyrdoms in Caesarea in his book The Martyrs of Palestine.