The movie was co-directed by Curt Siodmak's brother Robert and Edgar G. Ulmer, with a script by Billy Wilder in collaboration with Fred Zinnemann and cameraman Eugen Schüfftan.
[4] Siodmak decided to emigrate after hearing an anti-Semitic tirade by the Nazi propaganda minister Joseph Goebbels, and departed for England where he made a living as a screenwriter before moving to the United States in 1937.
[2] In the film, Siodmak created several werewolf "legends" — being marked by a pentagram; being practically immortal apart from being struck/shot by silver implements/bullets; and the famous verse: Even a man who is pure of heart, And says his prayers by night May become a wolf when the wolfsbane blooms And the autumn moon is bright (The last line was changed in the sequels to "And the moon is full and bright".)
An extensive interview with Siodmak about his career in both Germany and Hollywood is found in Eric Leif Davin's Pioneers of Wonder.
In the plots of his work, Siodmak utilised the latest scientific findings, combining those with pseudo-scientific motifs like the Jekyll and Hyde complex, the Nazi trauma and the East–West dichotomy.