Thaddeus of the twelve apostles was in fact Theudas, in a variant of his name.

Theudas, at the time Jesus was born as the FIRST-BORN son of Joseph the Essene, in March of 7 BC, was in charge of the Essene area of which the Qumran monastery is a part.  He was even then the leader of the Alexandrean Essene group called the "Egyptian Therapeautae".  Along with the "Magi", Theudas' group supported Jesus as the potential "Messiah" the Essene prophets were looking for of the lineage of King David.

The former Prodigal Son, he was now much older, remaining head of the Therapeautae, and as a moderate nationalist and leader of Alexandrian members [of the Essenes at Qumran] (who could vary in their loyalties between east and west) he could join with either of the other groups. His primary association, however, was with the tetrarch Antipas, who saved him, as Barabbas, from crucifixion."   Jesus and the Riddle of the Dead Sea Scrolls --- page 81

 "Barabbas", always a disciple and friend of Jesus during the 3 1/2 years during which Jesus was accepted and followed by the Essenes as the "Messiah" of the blood-line of King David, met with Jesus under the name "Nicodemus". In a story featured in John's Gospel  they together, Jesus and Theudas ("Nicodemus") adapted some Egyptian Theology with which Theudas was very familiar to apply to Jesus as the "Only-Begotten Son of God" a specific terminology applying only to Horus, the Son of Osiris in Ancient Egypt.