William van der Bilt I is a recurring character in the Gossip Girl television series. He is the grandfather of Nate Archibald and Tripp van der Bilt.
William van der Bilt is very proud of his family's political heritage and tries to convince Nate to follow the family business, having already convinced Tripp to do so. William appears to care for his family but is not above manipulating them to further his own agendas, such as when he asks Blair Waldorf to "talk" to Nate about going to Yale instead of Columbia.
Previously, he had refused to help Nate's mother when the Captain was charged with embezzlement, leading to a falling-out between his grandson and himself. In The Grandfather Nate reconnects with his van der Bilt family and his grandfather exerts his considerable influence over him, contributing to tensions with Vanessa and Blair. So far Nate has resisted William's suggestions regarding his future political career.