Carson Beckett

Extended knowledge of medicine, discovered the Ancient gene
2004: Joined the Atlantis expedition, in the Pegasus Galaxy, as Chief Medical Officer;
Created a serum which gave 46% of those who received it the Ancient Gene
2005: Developed a retrovirus that turned Wraith into humans
2006: Captured & unknowingly cloned by Michael, rescued by his teammates
2007: Successfully removed an explosive tumor from a patient, was killed when it exploded
2008: The clone was discovered & rescued from the planet M8G-352;
Suffered from a degenerative condition, placed in stasis while waiting for a cure
Eventually injected with a cure from Michael's database, sent to Earth
2009: Joined the USS George Hammond, returned to Pegasus with Atlantis