the cast of the first season consisted of joe flanigan starring as maj. john sheppard, david hewlett as dr. rodney mckay, rachel luttrell as teyla emmagan, torri higginson as elizabeth weir and rainbow sun francks as first lt. aiden ford. aiden ford was reduced to recurring character in season two and was replaced by jason momoa as the extraterrestrial human ronon dex in episode three of season two. francks continued to have a recurring role in season 2, until his character's death (although this was not confirmed). after torri higginson's departure as a main character from "stargate atlantis" after season 3, she was replaced by amanda tapping's carter from the sister show. paul mcgillion, robert picardo and jewel staite were also main characters. mcgillion became a main character in season two until season three as carson beckett, picardo replaced tapping as a main character as the new leader of the atlantis expedition as richard woolsey for season five, and staite portrayed jennifer keller as a main character in season five.