The names of Simon and Jude appear in New Testament lists of the apostles but little else is known about either. Since there are two apostles named Simon and two named Judas (Luke 6.14-16 and Acts 1.13), these are distinguished as Simon the Zealot and Judas the son (or the brother) of James, the others being Simon Peter and Judas Iscariot.
Simon is surnamed the Cananaean or the Zealot, names which refer to his zeal for the Law. Jude (Judas) is also called Thaddeus (Matthew 10.4 and Mark 3.18); the one mentioned of him outside of the lists is in John (14.22-23) where he is referred to as “Judas (not Iscariot)”.
Traditionally, both these apostles suffered martyrdoms. In a later tradition, Jude became a patron saint of so-called hopeless causes.