protomartyr

The first martyr for a given cause or in a given place. Used especially of the first Christian martyr, Saint Stephen.

The first martyr; the first of any series of martyrs; the first who suffers or is sacrificed in any cause; specifically, Stephen, the earliest Christian martyr.

The first martyr; the first who suffers, or is sacrificed, in any cause; — applied esp. to Stephen, the first Christian martyr.

Any of the first Christian martyrs.