Once & Future #15 was published by Boom! Studios on January 1, 2021, as part of a series that began in 2019. Kieron Gillen writes, and art comes from Dan Mora, Matias Bergara and Tamra Bonvillain. This 32-page issue features Sir Lancelot, Duncan McGuire, Bridgette McGuire, Rose and Elaine McGuire.