Rachel McAdams
Rachel McAdams will appear in "Doctor Strange," but no details about her character have been revealed. Pictured: McAdams attends Toronto International Film Festival on Sept. 12, 2015. Getty

Rachel McAdams is officially joining the Marvel Cinematic Universe (MCU). The “True Detective” alumna confirmed that she will join “Doctor Strange.”

McAdams’ casting isn’t too shocking. In July, she told the Los Angeles Times that she was being considered for the leading female role opposite star Benedict Cumberbatch, who is playing the titular character. “It's still super-early days, and I don't know where that's gonna go, if it's gonna go anywhere at all,” she said. Obviously, it went well for the 36-year-old. Though she told The Wrap the good news, she didn’t say who she’d play. That means it’s time for theories.

1. Clea – “Female lead” often refers to a love interest, so Doctor Strange’s wife is an obvious choice. Clea is the Sorceress Supreme of the Dark Dimension and has plenty of powers. Her abilities include “forming and throwing magical bolts of energy, conjuring objects and energies, teleporting, telekinesis, controlling others’ minds, and casting illusions,” according to Marvel. She helps Doctor Strange on many of his adventures. Also, she eventually joined the Defenders in the comics. The MCU is currently building the Defenders with their Netflix series, so this might be a character they want to introduce soon.

2. Donna Strange – No one ever said she’d be the romantic female lead. McAdams could be playing Doctor Strange’s sister. Donna is two years younger than her brother, and her tragic drowning accident deeply affects him as he starts medical school. Though Donna died at age 17 in the comics, the movie might not be going that far into Doctor Strange’s past, so they may have aged her a bit. Marvel movies are known to tweak the comics.

3. Linda Carter – Fans have been wondering if Linda Carter, a.k.a. Night Nurse, could be introduced in “Doctor Strange.” Night Nurse was introduced in “Marvel’s Daredevil” as Claire Temple (Rosario Dawson), and as Coming Soon notes, the producers said they didn’t use Linda’s name because a future movie had plans for her. “The feature side had plans for her down the road,” executive producer Steven S. DeKnight explained to /Film, “so that was the only time we ran into a conflict. So we just used another name.”

4. A Villian – McAdams might not be a good guy. Doctor Strange has plenty of enemies, and McAdams could easily be playing one. Though Chiwetel Ejiofor has already been cast as bad guy Baron Mordo, Doctor Strange might have more than one enemy in this flick.

In typical Marvel fashion, no clues have been given about her role, so it’s worth noting that McAdams might not be playing a comic book character. Even if the producers have given her a comic book role, she might not be playing a female character from the comics. Tilda Swinton was cast as Ancient One, who was a male character in the source material.

“Doctor Strange” hits theaters on Nov. 4, 2016.