Barabbas (Aramaic: Bar-abbâ, "son of the father") was the name of insurrectionary murderer whom Pontius Pilate freed at the end of the Passover feast in Jerusalem. (Matthew 27:16, Mark 15:7, Luke 23:18-19, and John 18:40).
Barabbas was most likely a member of the Sicarii, a military Jewish group that sought to overthrow the Roman occupation.
It is interesting to note that some early texts of the Gospel of Matthew present Barabbas' name twice as Jesus bar Abbas. According to the United Bible Societies' text, Matthew 27:17 reads: "...whom will ye that I release unto you? Jesus Barabbas (Greek: Iesous ton Barabbas) or Jesus which is called Christ (Greek: Iesous ton legomenon Christon)?"
Somewhere along the line, the "Jesus" was dropped of the Jesus Barabbas. In the 3rd century, Origen deliberately left out the "Iesous" in Iesous ton Barabbas for reverential considerations. He did not want the name Jesus to be associated with a sinner.