Dr. J. W. Müller is the evil German psychiatrist whose position and qualifications serve as a cover for more villainous activities, including mistreatment of patients, counterfeiting, and later criminal mercenary. Hergé considered Müller "a Rastapopoulos figure prepared to risk his own life. Müller frequently uses profanities such as "Kruzitürken" that are of Bavarian origin, suggesting his background to be Bavarian or Austrian, but he could also be Swiss or South-Tirolian. As with Rastapopoulos, his true nationality is never revealed.

The Adventures of Tintin (French: Les Aventures de Tintin) is a series of comic albums created by Belgian cartoonist Georges Remi (1907–1983), who wrote under the pen name Hergé. The series was one of the most popular European comics of the 20th century. By the time of the centenary of Hergé's birth in 2007, Tintin had been published in more than 70 languages with sales of more than 200 million copies.