He is always referred to as Doubting Thomas, but I wonder every Easter if maybe he got a bum rap.
Sure, the other Apostles believed and he didn't, but would they believe if Jesus hadn't appeared to them. And why wasn't Thomas there to see Him? Because unlike the others he wasn't locked up inside that room. He was out preaching the Gospel.
Not only that (Please correct me if this is wrong), but St Thomas was the only one of the twelve besides Peter to proclaim Jesus is God.