Person

James the Lesser

One of the Twelve apostles, listed in all four canonical apostolic lists as James son of Alphaeus (Matt 10:3; Mark 3:18; Luke 6:15; Acts 1:13). Called "the Less" (Mark 15:40, Iakōbos ho mikros, plausibly "the younger" or "the smaller") to distinguish him from James the Greater (son of Zebedee). The least-narrated of the Twelve in canonical material; tradition assigns him various later missions and a martyrdom, but the specific acta are weak.

Biographical sketch

Listed but not detailed: every apostolic list names him, but the Gospels contain no narrative material identifying him distinctively. He is the most obscure of the Twelve.
Father: Alphaeus, who is also named as the father of Matthew / Levi (Mark 2:14). Some traditions accordingly identify James the Lesser and Matthew as brothers, but this is uncertain, Alphaeus is a common enough name.
Mother: probably the "Mary the mother of James the Less and Joses" who watched the crucifixion (Mark 15:40; cf. Matt 27:56, "Mary the mother of James and Joseph") and visited the tomb (Mark 16:1). If so, this Mary is distinct from Mary the mother of Jesus, Mary Magdalene, and Mary the wife of Clopas (unless Clopas = Alphaeus, which has been historically argued but is uncertain).

Distinction from James the Just

A perennial historical question is whether James the Lesser (son of Alphaeus, one of the Twelve) is the same person as James the Brother of Jesus (who led the Jerusalem church). The codex follows the majority modern view that they are distinct:

The Gospels distinguish "His brothers" (the family of Jesus) from "His disciples" (Mark 3:31-35 places the brothers outside the disciples).
John 7:5 explicitly says "not even His brothers were believing in Him" during the ministry, incompatible with James the Just being one of the Twelve.
Paul distinguishes "the apostles" from "James the Lord's brother" (Gal 1:19), suggesting James the Just was apostolic-recognized but not one of the Twelve.
The Eastern and most Catholic tradition has historically identified them (and a few have identified all three Jameses, Lesser, Just, son of Alphaeus, as one person), but this is at the cost of strained reading.

Post-resurrection ministry

Patristic and traditional sources are thin and inconsistent:

Some traditions: James the Lesser preached in Syria, Egypt, or Persia.
Martyrdom: traditions variously give crucifixion in Egypt, stoning in Jerusalem (typically conflating with James the Just), or being beaten to death with a fuller's club.
Symbol: Christian iconography typically gives James the Lesser the fuller's club (the same iconographic symbol some traditions assign to James the Just, indicating the historical confusion).
Confidence level: legendary; no early or strong patristic attestation distinct from James the Just.

Theological themes

The Lesser's near-anonymity raises a homiletic point that the New Testament implicitly affirms: not every apostle needs to be a major narrative figure for the apostolic foundation to hold. The Twelve were a collective body witnessing Christ; the Spirit did not require each one to be individually famous. James the Lesser's faithfulness is preserved in the bare-list inclusion, and his presence at the foundation of the church is sufficient theological significance.