Disney+'s WandaVision series might feature one of Doctor Strange's biggest villains.

Murphy's Multiverse is reporting a source claims Nightmare has been cast in WandaVision and will serve as the Disney+ series' villain. The outlet says it has, at this time, been unable to get corroboration from another source, so this should be considered a rumor and thus taken with a grain of salt.

RELATED: Doctor Strange's Benedict Cumberbatch Wants an All-Female Marvel Film, Too

Nightmare is expected to play a role in Doctor Strange in the Multiverse of Madness as co-writer C. Robert Cargill revealed last April that he and Derrickson have the villain in mind for their film. There were originally plans for Nightmare to appear in Doctor Strange, but Marvel Studios President Kevin Feige reportedly shut that idea down. This information would also match claims WandaVision will directly connect to Doctor Strange in the Multiverse of Madness.

Created by Stan Lee and Steve Ditko, Nightmare first appeared in 1963's Strange Tales #110. The immensely powerful demon rules the Dream Dimension and gets power by tapping into the psychic energies of unconscious people.

WandaVision stars Elizabeth Olsen as Scarlet Witch, Paul Bettany as Vision, Randall Park as Agent Jimmy Woo, Kat Dennings as Darcy Lewis, Teyonah Parris as Monica Rambeau and Kathryn Hahn. The limited series will premiere on Disney+ in spring 2021.

KEEP READING: WandaVision's Elizabeth Olsen Throws Shade at Her Marvel Co-Stars