The 100th episode of Gossip Girl on Monday night was chock full of revelations, including the show's big mystery: the identity of Gossip Girl herself. And be warned, if you haven't seen it yet, spoilers lie ahead.

For four and a half seasons, viewers have known GG's voice -- as provided by House of Lies star Kristen Bell -- but have never seen the trouble-stirring gossiper's face.

But in the final scene of the episode, which featured the wedding of Blair and Prince Louis, the camera panned to Gossip Girl's face to reveal that she is . Georgina Sparks (Michelle Trachtenberg).

One of the series' all-time best troublemakers, Georgina had done her best to break up the wedding earlier in the episode.

Two more spoiler/shockers from the wedding installment: After blowing off true love Chuck to marry the prince, Blair learned Louis didn't marry her with the best intentions. And she responded by running off with Dan, for whom Blair's BFF Serena had just professed her undying love.