I havn't seen Atlantis, or any other sub-series, infact. i've only ever watched StarGate : SG1. Col. O'Neil, Maj. Carter, Teal'c, and Dr. Jackson. (Of course Jonas Quinn was in for a while.)
What about Mitchell and Vala?
You are way behind.
On series 10 now, Vala came in 8.
Actually Vala was no regular until season 9