Last names were not used at that time in Israel. Instead, a person would be known as so-and-so from the town they were from. Judas was Judas Iscariot, which means "Judas from Kerioth."
Judas is mostly known for being the disciple that betrays Jesus. His betrayal occurs when he tells the Roman soldiers and the Jewish leaders that wanted to get of Jesus about Jesus' whereabouts....