A martyr is a person killed for supporting a religious or other cause. Often, his or her death will inspire others to take up the cause. The original martyr was Justin Martyr, killed for his faith in Christ in 165 AD. Many of the early Church Fathers were martyred. In fact, according to tradition, only one of the Twelve Disciples (The Apostle John) died of old age.
Martyrdom of 10,000 Christians by Albrecht Dürer