Star Wars Celebration is all about fandom and easter eggs and news, and the people behind Star Wars love to lean into that fan interest. So, during today's Ahsoka panel at the London ExCel, Ahsoka showrunner Dave Filoni confirmed that David Tennant will be reprising his role as the voice of Huyang in the live action Ahsoka show.
Huyang first appears in The Clone Wars as a very, very old droid who teaches younglings how to wield their lightsabers. He also happened to have the plans for all the lightsabers ever made-- which made him a very valuable resource.
Huyang was later damaged in an attack, but we now know (from the Ahsoka trailer and from Filoni's confirmation) that he's back and still in Ahsoka's world. We'll have to see how exactly he fits into Ahsoka's life now.