Re: Unexpected fan favorites who take over the show?
Well the thread has gone "off point" more than once with posts bringing up examples that don't quite fit the premise. Wasn't Xena a re-occuring guest-star rather than a supporting character? Fraiser was a one off character who goes from that to reoccuring to regular to his own spinoff. Sheldon as noted was always a lead in TBBT, who often has his own story in episodes. Howard seems to be more of a breakout, going from a supporting role to having entire episodes revolve around him. ( more so with the addition of Bernadette)
As for Mr. T and the A-Team, my memories of the show has dimmed, but I never got the impression BA was the central character/lead.
The boring one, the one with Khan, the one where Spock returns, the one with whales, the dumb one, the last one, the one with Kirk, the one with the Borg, the stupid one, the bad one, the new one, the other one with Khan.