The other person called "the son of perdition," is the Beast of Revelation 13:1-10. First, notice the Beast fits the description of him in 2 Thessalonians 2:3-4 where we read, "Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition; who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God."
Second, notice that he will be killed by the sword (Rev. 13:3), for we are told that "he that killeth with the sword must be killed with the sword" (Rev. 13:10). The Beast actually dies in Revelation 13:3, and is then indwelt by Satan and brought back to life (Rev. 13:4). We know that the Beast was brought back to life because Revelation 19:20 says, "And the Beast was taken, and with him the False Prophet that wrought miracles before him, with which he deceived them that had received the mark of the Beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone."
So why are Judas and the Beast (Antichrist - see 1 Jn. 2:18, 22), each called "the son of perdition?" The Greek word translated "perdition" is ἀπώλεια (apōleia), which actually means "destruction." In fact, it is translated "perdition" eight times and "destruction" five times. The moment Satan enters into them, their total focus is on the destruction of God's children. Judas sought to destroy God's only begotten Son, and the Beast will attempt to destroy the saved Jews during the second half of the Tribulation. It is in the midst of Daniel's Seventieth Week that the eyes of the Jews are opened, and they realize Jesus was their Messiah after all (Dan. 9:27; Mt. 24:15; Rom. 11:25-26).
There are two sides in the cosmic war: the sons of perdition verses the sons of God.
Unless you trust in Jesus, you remain a child of the devil (Mt. 13:38; Jn. 8:44)!