
The recently announced Super Mario Galaxy Movie hasn’t even landed yet, but fans are already connecting dots faster than Mario on a Rainbow Road speed run. The first trailer for Nintendo and Illumination’s cosmic sequel gave viewers everything they hoped for—floating planetoids, Lumas, Launch Stars, and the long-awaited debut of Rosalina. But the real lightning strike came with the casting reveal that Brie Larson is voicing the mysterious cosmic princess. And for fans, that instantly reignited one of the Mario franchise’s biggest, oldest theories.
According to reporting from ComicBook.com, Rosalina’s expanded presence in the trailer—as well as Larson’s A-list casting—strongly suggests the film may finally address a question fans have debated since 2007: Is Princess Peach secretly Rosalina’s sister? It’s a theory supported by years of fan analysis, developer comments, and a surprisingly lore-rich in-world book. Now, the movie may be ready to make it canon.