Article: Walt Disney Parks and Resorts plans on creating original Marvel attractions at their theme parks, with Hong Kong Disneyland becoming the first Disney theme park to feature a Marvel attraction. Due to the licensing agreement with Universal Studios, signed prior to Disney's purchase of Marvel, Walt Disney World and Tokyo Disney are barred from having Marvel characters in their parks. However, this only includes characters Universal is currently using, other characters in their "families" (X-Men, Avengers, Fantastic Four, etc.), and the villains associated with said characters. This clause has allowed Walt Disney World to have meet and greets, merchandise, attractions and more with other Marvel characters not associated with the characters at Islands of Adventures, such as Star-Lord and Gamora from Guardians of the Galaxy as well as Baymax and Hiro from Big Hero 6.

Question: The contract with what non-Disney studio prevents some parks from using Marvel characters?
Universal Studios