Several NT men had this name:
1/. A half-brother of Jesus, and who wrote the book of James (Mt 13:55; Gal 1:19; Jas 1:1). It is assumed that he became a follower after Jesus had been crucified. He became a church leader in Jerusalem and is mentioned throughout Acts (eg. Act 12:17, 15:13, 21:18).
2/. The disciple James. Along with his brother John, both were early disciples of Jesus and, together with Peter, formed an inner circle of three within the 12 disciples (Mt 4:21,22; Mk 9:2). Zebedee was his father. He was the first (and only recorded) of the 12 disciples to be martyred (Act 12:2).
3/. Another James, the son of Alphaeus was also in the original 12 disciples (Mt 10:3; Act 1:13).