Madame Zarkov was a live-performed character created for the Adventurers Club of Walt Disney World. She would later be incorporated into Big Thunder Mountain Railroad at the Magic Kingdom with additional allusions to the Museum of the Weird and S.E.A.. The Museum of the Weird is an unbuilt attraction planned to be an extension of the Haunted Mansion in Disneyland's New Orleans Square which was developed by imagineer Rolly Crump. Zarkov's connection to the Mansion might be inspired by, "Madame Z", a character created by Marc Davis for the Haunted Mansion who later evolved into Madame Leota.
The Adventurers Club
Zarkov was an irregular character at the club who typically served as a replacement for regular-character Samantha Sterling. During the club's later performances they would both often appear in the attraction more regularly.
Big Thunder Mountain Railroad
In the queue for this attraction, Madame Zarkov is mentioned by Jason Chandler in a letter sent to Barnabas T. Bullion referring to the supernatural occurrences of Big Thunder Mountain.