Following the announcement that FX's Legion will end with its upcoming third season, the production has revealed the casting of David Haller's biological parents: Gabrielle Haller and Professor Charles Xavier.According to a tweet from the official Legion Twitter, actor Harry Lloyd will play Professor X, while Gabrielle will be played by Stephanie Corneliussen. Lloyd is known for his roles as Jeremy Baines on Doctor Who and Viserys Targaryen on Game of Thrones. Corneliussen is known for her role as Joanna Wellick on Mr. Robot.RELATED: FX's Legion To End With Season 3

In X-Men comic book lore, David Haller is the son of Xavier and Gabrielle Haller, a catatonic Holocaust survivor. Xavier met and helped Gabrielle to psychically heal while working at an Israeli psychiatric facility. The two subsequently had an affair, which resulted in the birth of David, himself a powerful mutant. The show has made several allusions to David's lineage, but it wasn't certain if we'd get to actually see his parents on screen.

It's unclear at this time how Charles Xavier and Gabrielle will factor into the show. However, Lloyd and Corneliussen are fairly young, aged 35 and 31, respectively. This seems to hint that the versions of the characters fans will get to see won't be particularly old. In comparison, actor Dan Stevens -- who plays David Haller -- is, at age 36, older than both actors playing his parents.

Although he never explicitly confirmed Professor X would appear, creator Noah Hawley indicated at New York Comic Con in 2016 that the character's eventual inclusion was likely. "I don't think you can tell that story without that element to it, so I will say you probably will," Hawley said.

RELATED: Legion Season 3 Casts a New Marvel Mutant

Legion returns to FX in 2019. The series stars Dan Stevens, Rachel Keller, Jean Smart, Bill Irwin, Amber Midthunder, Jeremie Harris, Aubrey Plaza, Jemaine Clement, Hamish Linklater and Navid Negahban.