The disciple known as “Doubting Thomas” was Thomas, one of Jesus’ twelve apostles.
In John 20, Thomas says he will not believe that Jesus has risen unless he sees the marks of the nails and touches Jesus’ wounds. Jesus later appears to the disciples and invites Thomas to examine the evidence. Thomas responds with the confession, “My Lord and my God!”
The Gospel of John does not use the modern nickname “Doubting Thomas.” It presents the episode as part of a broader movement from uncertainty to belief. The passage also preserves the detail that Thomas was absent from the first appearance of the risen Jesus to the gathered disciples.
Thomas is also called Didymus in John; that name means “Twin” in Greek. The Bible does not identify the person who was his twin, so proposed names are later traditions rather than stated Gospel facts.