3) Clea

Like Starfox, this sorceress (Charlize Theron) appeared out of nowhere during a Marvel movie mid-credits scene, this time in Doctor Strange in the Multiverse of Madness. Clea was one of the evil Dormammu’s disciples but ended up as Strange’s wife for a time in the comics, so she has multiple ties to the ex-Sorcerer Supreme. In the MCU, she shows up for all of 20 seconds, tells Strange he created an incursion and takes him to help fix it. Marvel clearly has some plan for Clea, given they hired Theron to play her, but there’s not even a hint that a third Doctor Strange movie is on the way, and it would be very weird if she joined the Avengers to help fix the multiverse in Kang Dynasty or Civil War—there are many, many more popular characters floating around the MCU who should join their ranks first.