In the New Testament
James, son of Zebedee and older brother of John, was a fisherman on the Sea of Galilee, called by Jesus alongside his brother while they were mending their nets in their father's boat (Matthew 4:21–22; Mark 1:19–20). Jesus nicknamed James and John Boanerges, "Sons of Thunder" (Mark 3:17) — almost certainly a comment on their temperament, consistent with the episode where the brothers wanted to call down fire from heaven on a Samaritan village that refused to welcome Jesus (Luke 9:54), and with their mother's (or, in Mark's version, their own) request for the seats of highest honor in Jesus's kingdom, which the other ten apostles resented (Matthew 20:20–24; Mark 10:35–41). James was part of Jesus's innermost circle alongside Peter and John — present at the Transfiguration (Matthew 17:1), the raising of Jairus's daughter (Mark 5:37), and Gethsemane (Matthew 26:37).
Martyrdom — the one death recorded in Scripture itself
James holds a distinct place among the Twelve: his death is the only apostolic martyrdom explicitly recorded within the New Testament itself, rather than resting solely on later tradition. Acts 12:1–2 states plainly that King Herod Agrippa I "killed James the brother of John with the sword" — almost certainly beheading — as part of a broader persecution of the Jerusalem church, likely around AD 44. Herod's own death follows just a few verses later (Acts 12:19–23), struck down, in Luke's telling, for accepting worship as though he were a god.
The Santiago de Compostela tradition
A much later (and historically far less certain) Spanish tradition holds that James had preached in Spain before returning to Judea to be martyred, and that his body was then miraculously transported back to Spain, where it was later discovered and became the burial site of Santiago de Compostela — one of medieval and modern Christianity's most significant pilgrimage destinations, and the origin of the "Camino de Santiago" pilgrim routes still walked today. This tradition has essentially no early historical attestation and developed centuries after James's death, but it became enormously important to medieval Spanish Christian identity, particularly during the Reconquista, when Santiago ("St. James," rendered as Matamoros, "Moor-slayer," in some medieval military iconography) became a rallying figure — a detail worth knowing honestly, since it shows how quickly a genuine apostle's memory can be pressed into service for causes far removed from anything in the Gospels.
Why it matters
James's Scripture-confirmed martyrdom is a sober anchor point for thinking about the other apostles' more legend-dependent traditions: it shows that real, early, violent persecution of the apostolic leadership was already underway within roughly a decade of the resurrection, and that "Sons of Thunder" who once wanted to call down fire on their enemies ended up being the ones who suffered violence themselves rather than dealing it out.