Daniel Jackson

Archaeologist, expert in ancient writing, languages & cultures
Ostracized from the scientific community for his radical theories, such as the Pyramids being built as alien ship Landing Sites
1996: Enlisted by the air force to deciphered & unlocked the Stargate;
Journeyed to Abydos, decided to stay, got married & made a life for himeslef
1997: Joined SG-1 to help rescue his wife who had become a Goa'uld host
1999: Remained permanently with SG-1 after his wife was killed
2002: Ascended to avoid death by radiation poisoning
2003: Helped Abydos ascend after Anubis attack, descended back to a mortal
Rejoined SG-1 were he remains to this day