Stephen was the first Christian to be martyred, but he was not the first apostle to be martyred. He was a faithful Christian man that was one of the first deacons (see Acts6:5,8; 7:59).
The first of the apostles to be martyred was James, the greater. He was one of the sons of Zebedee. The apostle John was his younger brother. His martyrdom is mentioned in Acts 12:2. It is estimated this was around 44 AD. It was during a time of persecution launched against the church by Herod Antipas.
Saint James the Greater was killed by King Herod and the first of the apostles to die. He was martyred in AD44.
John
He was martyred while in prayer in India.
Matthew the Apostle is believed to have been martyred by being stabbed to death in Ethiopia.
The apostle Matthew is believed to have been martyred by being stabbed to death in Ethiopia.
Because that is where St. Peter the Apostle was martyred.
All the Apostles were martyred except John, who died of old age, and the Apostle Paul was beheaded by Nero in 67-68AD [Roman and Hebrew calendars do not coincide].
Because that is where St. Peter the Apostle was martyred.
St. Philip the Apostle was martyred about the year 80 at Hierapolis, Phrygia.
We know nothing about what happened to any of the apostles, except perhaps Judas. There are various traditions from the second to the fourth century that claim that all the apostles were martyred, except the apostle John. These traditions are not to be taken as historical accounts.
The first apostle to be martyred was James, the son of Zebedee. According to the New Testament, he was executed by beheading on the orders of King Herod Agrippa I, as described in Acts 12:1-2. His martyrdom is significant in the early Christian church, highlighting the dangers faced by the apostles in spreading their message.
Yes, Saint Thomas the Apostle is believed to have been martyred. According to tradition, he was stabbed to death with a spear in India.