In both the novels and the television adaption, Gossip Girl is a blogger whose true identity is never revealed. It is later ultimately revealed in the television series finale to be Dan Humphrey, although Georgina Sparks and Serena van der Woodsen both have times where they take over the blog.
Is Dan the Gossip Girl?
Dan reveals at the end of the series that he was Gossip Girl from the beginning for a way for him to win Serena by writing himself into the Upper East Side, a task he succeeded in by the end of the series. In the finale, Dan and Serena get married, surrounded by friends and family.
Who turned out to be the Gossip Girl?
To the surprise of even many devoted fans, Dan Humphrey (Penn Badgley) turned out to be the long-elusive Gossip Girl herself. Or himself. It made sense in a way. Dan is the writer in the group and he came to the show's rich, entitled scene in the beginning as an outsider, though he integrated well over the years.