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 is mentioned but is never seen during the first season.
In Summer Kind of Wonderful, Nate's mother, Anne Archibald, reveals to Nate that William was not happy with her involvement in helping his father, Howard Archibald, skip town in Much 'I Do' About Nothing, and cut her off financially.
In The Magnificent Archibalds, it's revealed Howard is planning to hold Nate and Anne for ransom to get William to give him money. However, Nate turns his father in and the plan never comes to fruition.
In The Grandfather, Nate reluctantly attends the family reunion hosted by William, along with Dan and Vanessa. During which, Nate and his grandfather make amends, after fighting over Howard. Nate admits that he assumed William was angry and disappointed, but is surprised when William tells him he has never been more proud of him. However, William begins to groom Nate to follow the political legacy and convinces him to take a summer internship at the mayor's office. This causes tension between Nate and Vanessa, as they already had plans to travel that summer. In Seder Anything, Nate and Blair have gotten back together and are planning to attend his cousin Tripp van der Bilt's wedding to Maureen van der Bilt. Upset her college plans didn't work out, Blair makes a deal with William to convince Nate to attend Yale University. However, before she can, Nate finds out from Tripp that William is the one who had Howard originally investigated by the FBI. Before he leaves the party, William tells him about his deal with Blair.
When Nate shows up at the van der Bilt's annual polo match with his new girlfriend Bree Buckley in Reversals of Fortune, William isn't angry like Nate was expecting. He gives them a car to get back to the city in. However, the family has always had a rivalry with the Buckley's and William tells Tripp they might now have a way to take them out. In Enough About Eve, Serena finds out Nate and William were using her and Carter Baizen to screw the Buckley's over. But she catches on soon enough to warn them about their plan.
In The Grandfather: Part II, Tripp, who is running for Congress, is behind in the polls until he saves a stranger from drowning. When Vanessa discovers it was a set up, Nate and Tripp instantly blame William, who denies any involvement. Nate decides to take responsibility, and Tripp wins the election. At the end of the episode, Maureen reveals to William that she was the one who set it up, in order to get William out of the picture.
William is mentioned, but does not appear in season four.
Nate meets Diana Payne in Los Angeles, and agrees to work for her at the New York Spectator in Manhattan. However, it's eventually revealed that William is the majority shareholder in the newspaper and made Diana hire Nate to help him find a career path. In Rhodes to Perdition, Nate receives a tip that Maureen is having an affair and cheating on Tripp, however he suspects she's lying about the affair. Also, William invites Nate to be his guest at Camp David, angering Tripp. In Riding in Town Cars With Boys, Blair and Chuck get into a serious car accident in a car that was ordered for Nate to take him to the airport. In Father and the Bride, William, Nate, and Serena trick Tripp into telling them about how he was responsible for the faulty car. He blames his actions on the competition William set up between him and Nate for his approval. Nate doesn't disagree, and reveals to William he has new investors set up to back The Spectator and no longer needs him. This is William's last appearance in the series.