Check out list of celebrities who attended Billie Eilish's 21st birthday bash

Billie Eilish celebrated turning 21 with her favorite people by her side.

The Bad Guy singer painted the town red with a Christmas-themed party over the weekend.

The star-studded bash was attended by Lil Nas X, Hailey Bieber, Kendall Jenner, Jesse Jo Stark, Dove Cameron, Avril Lavigne, Eric Andre, and boyfriend Jesse Rutherford.

Eilish and Rutherford decked out in Santa Claus-inspired outfits, while other celebrities also followed suit.

Rapper Lil Nas X also took to his Instagram stories to upload snippets from the bash.