Peter, Andrew, James (son of Zebedee), John, Philip, Bartholomew, Thomas, Matthew, Judas, James (son of Alphaeus), Thaddeus, Simon (the Zealot), and James (son of Alphaeus) are the twelve apostles.
Judas killed himself (Matthew 27:1–5), and Jesus told St. John, the son of Zebedee, to take care of his mother Mary (John 19:25–27). There is a strong tradition that he died of natural causes in Ephesus when he was old.
The Bible says that King Herod Agrippa I killed James (the Greater), the son of Zebedee (Acts 12:1-3). However, the king himself was killed by an angel not long after that (Acts 12:19-23). In the early Church, there is a lot of evidence that St. Peter, who was in jail when James was killed (Acts 12:3), was killed in Rome around twenty years later with St. Paul.
St. James (the Lesser), son of Alphaeus, is often linked to St. James, “the brother” or relative of Jesus, who was the bishop of Jerusalem in Acts 15 and was stoned to death in Jerusalem in the 60s A.D., according to Eusebius (Church II, 23) and Josephus, a famous Jewish historian of the time. Pope Emeritus Benedict XVI said, “Among experts, the question of whether James son of Alphaeus and James “the brother of the Lord” are the same person is debated.”
Tradition says that St. Thomas preached in India and was killed there for his faith, which Pope St. John Paul II confirmed during his apostolic visit in 1986. Tradition also says that St. Andrew was killed around the year 60 A.D. by a form of crucifixion.
St. Bartholomew, who many scholars know as “Nathaniel,” is also thought to have died as a martyr, either by being beheaded or by being flayed alive.
St. Philip may have been killed at Hierapolis, which is now in Turkey. However, that may be the tomb of St. Philip the deacon, which is mentioned in the Acts of the Apostles.
The Roman Martyrology says that St. Matthew was killed for his faith, but it is not clear how he died.
Tradition also says that St. Simon (the Zealot), who was the son of Clopas and was also called Jude, and St. Jude, who was also an apostle, were both killed (Thaddeus). Both the Roman Martyrology and the Roman Canon mention them (Eucharistic Prayer I).