Doctor Strange in the multiverse of Madness referenced a few prominent characters from MCU, both directly and indirectly; however, they did not appear in the events of the film, despite being mentioned.
The film featured several fan-favorite characters, not only from the MCU but also from outside the established Marvel Cinematic Universe, as the multiverse starts crumbling around them, as a result of the meddling of the Scarlet Witch and Doctor Strange. Read on to find out about the references.
Donna Strange
At the time of the confrontation between Stephen Strange and his evil doppelganger, it is disclosed that the former once had a sister named Donna, whom he could not rescue from drowning in a frozen lake. Until this moment, there was no prior indication of Stephen having any siblings. This revelation sets an entirely fresh perspective on his cold and arrogant demeanor that was unexplained for years.
Chthon
Chthon in MCU is the ancient demon who had cast a curse on Wanda upon her birth. This film directly mentions the supernatural entity when Wong and Wanda visit his temple on the Wundagor mountain, seeking a throne that is meant for the Scarlet Witch. With the inclusion of Chthon, MCU seems willing to increasingly embrace Wanda’s darker origins derived from the comic series.
Dormammu
The mid-credits scene in the film introduces a sorceress hailing from the Dark Dimension, Clea, who warns Stephen about a coming incursion with an alternate universe. The comic lovers know that Clea has an intimate connection to the Big Bad from the original Doctor Strange film. The comic origin of Clea reveals that she is Dormammu’s niece, who is far more virtuous than her uncle.
Valeria and Franklin Richards
Wanda after entering the Illuminati chamber, is confronted by the Fantastic Four’s Reed Richards, who reveals he has his own children. This major reference points at Valeria and Franklin Richards, the children of Susan and Reed Storm in the comics.
Sue Storm
After confronting Mister Fantastic, Wanda asks him about the mother of his children, to find out if she is still alive, and Reed confirms that she is fine. This, indeed, is a direct reference to Susan Storm, a.k.a. The Invisible Woman, who will most likely join the MCU in the coming years, along with the other heroes of the Fantastic Four.
While the movie features an abundance of old as well as new characters, it also leaves some of them out of action compelling the audience to speculate what might happen in the future.