Stargate

It might be a minority view, but I loved Jonas Quinn's character! Why? Because he made Teal'c a fully fledged [/edit] character. The both of them interacted so well. Teal'c was part of the main cast since episode one, but he never felt like a real person with their own emotions until season 6.

Christopher Judge is an incredible actor, but until Corin Nemec came along he wasn't allowed to be a whole person with their own agenda. Even small stuff, like not sharing his ice cream in "Prometheus" / "Unnatural Selection", would have been unthinkable before Jonas came along.

I think, retrospectively, telling Jonas to ~~fuck off~~ be with his people when Daniel came back hurt the series in the long run. Corin was a good actor, and Jonas was a good character.