The Merlin you're referring to is actually still running. It's a BBC show and has been renewed for a third season. NBC aired the first season in the US. Syfy is currently airing the second season.Hope it's actually good and not tween bullshit like that Merlin thing a little while ago.
Speaking of Merlin, I really liked that Sam Neil miniseries from way back when. That was fun. The more recent sequel/reboot/whatever the hell they did was shit, but the original was sweet.
In fact, as it happens, there's a new episode on in ten minutes . . . .