De cast van het derde seizoen van The Leftovers bestaat uit Justin Theroux, Carrie Coon, Amy Brenneman, Kevin Carroll, Christopher Eccleston, Scott Glenn, Lindsay Duncan, Regina King, Jovan Adepo, Janel Moloney, Margaret Qualley, Jasmin Savoy-Brown, Liv Tyler en Chris Zylka.
Showrunner Damon Lindelof zei eerder over het laatste seizoen:
“I have never, ever experienced the level of creative support and trust that I have received from HBO during the last two seasons of ‘The Leftovers. Tom, myself and our incredible team of writers and producers put tremendous care into designing those seasons as novels unto themselves…with beginnings, middles and ends. As we finished our most recent season, it became clear to us that the series as a whole was following the same model…and with our beginning and middle complete, the most exciting thing for us as storytellers would be to bring ‘The Leftovers’ to a definitive end. And by ‘definitive,’ we mean ‘wildly ambiguous but hopefully mega-emotional,’ as all things related to this show are destined to be.”