Best known for playing the titular role in the Broadway National Tour of Hedwig and the Angry Inch, Mason can be seen as Ian in NBC's Quantum Leap sequel series, Gren in the Netflix live action adaptation of Cowboy Bebop, Desire in Neil Gaiman's The Sandman, and in Amazon's Critical Role: The Legend of Vox Machina. They can also be found in the film Before You Know It,  and such TV shows as Broadway or Bust and Becoming and Artist on PBS, or iCarly and Bucket and Skinner's Epic Adventures on Nickelodeon. Mason was featured in the podcast musical Loveville High as the series' Bowie obsessed genderqueer high schooler, Jendrix. Most recently, they starred as the Emcee in the Olney Theatre Center's critically acclaimed production of Cabaret (for which they earned a Helen Hayes Award for Best Leading Performer in a Musical), and starred in the Pulitzer Prize winning play I Am My Own Wife at the Long Wharf Theatre January-March 2020.