The term apostle comes from the Greek apóstolos (ἀπόστολος) – formed from the prefix apó- (ἀπό-, 'from') and root stéllō (στέλλω, 'I send, I depart') – originally meaning 'messenger, envoy'. It has, however, a stronger sense than the word messenger, and is closer to a 'delegate'.

Each of the four listings of apostles in the New Testament indicate that all the apostles were men. According to Christian tradition they were all Jews. The canonical gospels and the book of Acts give varying names of the Twelve Apostles. The list in the Gospel of Luke differs from Matthew and Mark on one point. It lists "Judas, the son of James" instead of "Thaddaeus". All listings appear in three groupings, always with the same four apostles in each group. Each group is always led by the same apostle, although the order of the remaining three names within the group varies. Thus, Peter is always listed first, Philip is always listed fifth, and James, son of Alphaeus is always listed ninth. Judas Iscariot is always listed last.

Unlike the Synoptic Gospels, the Gospel of John does not offer a formal list of apostles. Although it refers to "the Twelve", the gospel does not present any elaboration of who these twelve actually were, and the author of the Gospel of John does not mention them all by name. There is also no separation of the terms "apostles" and "disciples" in John.

According to the New Testament there were only two pairs of brothers among the Twelve Apostles: Peter and Andrew, the sons of Jonah, as well as James and John, the sons of Zebedee. Since the father of both James, son of Alphaeus and Matthew is named Alphaeus, according to the tradition of the Eastern Orthodox Church the two were brothers as well. According to the tradition of the Catholic Church based on the writing of the Apostolic Father Papias of Hierapolis the apostles James, son of Alphaeus, and Thaddaeus were brothers and sons of Alphaeus (named also Clopas) and his wife Mary of Clopas who was the sister of the mother of Jesus. The Golden Legend, compiled by Jacobus de Voragine in the 13th century, adds to the two apostles also Simon the Zealot.
Peter, James son of Zebedee, and James's brother John formed an informal triumvirate among the Twelve Apostles in the Gospels. Jesus invited them to be the only apostles present on three notable occasions during his public ministry: the Raising of Jairus' daughter, the Transfiguration, and the Agony in the Garden of Gethsemane.

At the time of the Early Christian Church as a leading trio among the apostles were recognized Peter, John and James, brother of Jesus, known collectively as the three Pillars of the Church. According to the tradition of the Catholic Church based on the writing of Jerome this James is identified with the apostle James, son of Alphaeus.

Two of the leading triumvirate, Peter and John, were additionally sent by Jesus into the city to make preparation for the final Passover meal (the Last Supper), and were also the o…

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Of the Twelve Apostles to hold the title after Matthias' selection, Christian tradition has generally passed down that all of the Twelve Apostles except John were martyred. It is traditionally believed that John survived all of them, living to old age and dying of natural causes at Ephesus sometime after AD 98, during the reign of Trajan. However, only the death of his brother James who became the first Apostle to die in c. AD 44 is described in the New Testament. (Acts 12:1–2)

Matthew 27:5 says that Judas Iscariot threw the silver he received for betraying Jesus down in the Temple, then went and hanged himself. Acts 1:18 says that he purchased a field, then "falling headlong he burst open in the middle and all his bowels gushed out".

According to the 18th-century historian Edward Gibbon, early Christians (second half of the second century and first half of the third century) believed that only Peter, Paul, and James, son of Zebedee, were martyred. The remainder, or even all, of the claims of martyred apostles do not rely upon historical or biblical evidence, but only on late legends.
Relics of the apostles are claimed by various churches, many in Europe.
• Andrew: buried in Cathedral of Saint Andrew, Patras, Greece
• Bartholomew: buried in the Basilica of Benevento, Italy, or Basilica of St. Bartholomew on the Island, Rome, Italy
• James the Great: buried in Santiago de Compostela Cathedral in Santiago de Compostela, Galicia, Spain
• James, son of Alphaeus: buried in the Cathedral of St. James in Jerusalem or the Church of the Holy Apostles in Rome.
• John: no relics. The opening of his tomb (in the Basilica of St. John, Ephesus) during Constantine the Great's reign yielded no bones, giving rise to the belief that his body was assumed into heaven.
• Judas Iscariot: buried at Akeldama near Jerusalem (per the Gospel of Matthew and Acts of the Apostles).
• Jude Thaddeus: buried in St. Peter's Basilica under the St. Joseph altar with St. Simon the Zealot; two bones (relics) located at National Shrine of St. Jude in Chicago; other relics claimed by Reims Cathedral and Toulouse Cathedral.
• Matthew: buried in the Salerno Cathedral, Italy.
• Matthias: buried in the St. Matthias' Abbey in Trier, Germany.
• Paul: relics located in the Basilica of Saint Paul Outside the Walls in Rome; the skull located in the Archbasilica of Saint John Lateran, alongside the skull of St. Peter.

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