Agatha’s final major storyline involves her quest to control the Darkhold. Corina, from Agatha’s original coven, resurfaces as the villain Korrosion, intent on ending the world

Agatha All Along's premiere references Nicholas Scratch in the MCU, Agatha's son who becomes a powerful villain in the original Marvel Comics.

While Agatha is breaking down the title of the book stolen from the library, a paper under her notepad features "Bellevue," a fun little Easter egg. In the comics, Bellevue Hospital in New York is a recurring location for many Marvel heroes and villains, including the Night Nurse, Daredevil, Ms. Marvel, and Bullseye.