 | Boris Karloff als Dr. Friedrich Hohner |
 | Susanna Foster als Angela Klatt |
 | Turhan Bey als Franz Munzer |
 | Gale Sondergaard als Luise |
 | Thomas Gomez als Count Seebruck |
 | June Vincent als Marcellina |
 | George Dolenz als Amato Roselli |
 | Ludwig Stössel als Carl Baumann |
 | Jane Farrar als Jarmila Vadek |
 | Ernö Verebes als Brunn |
 | Lotte Stein als Mama Hinzl |
 | Scotty Beckett als The King |
 | William Edmunds als Leon, Theatre Concierge |
 | Maxwell Hayes als Count Romburg |
| Dorothy Lawrence als Miss Metzger |
| Bella Lewitzky als Dancer (Uncredited) |
 | Jack Richardson als Musical Conductor (Uncredited) |
| Polly Bailey als Cleaning Woman (Uncredited) |
 | Stuart Holmes als King's Consul (Uncredited) |
 | Eddie Polo als Stagehand (Uncredited) |
| Paul Power als Reporter (Uncredited) |
 | Ernie Adams als Man in Audience Next to Franz (Uncredited) |
 | Gertrude Astor als Woman in Audience Behind Franz (Uncredited) |
 | Grace Cunard als Backstage Maid (Uncredited) |
 | William Desmond als Backstage Technician (Uncredited) |
 | Francis Ford als Backstage Attendant (Uncredited) |
 | Louis Payne als Audience Member (Uncredited) |
 | Anne Cornwall als Audience Member (Uncredited) |
 | Rudy Bowman als Audience Member (Uncredited) |
 | William H. O'Brien als Audience Member (Uncredited) |
 | Helen Gibson als Audience Member (Uncredited) |
 | Maurice Costello als Audience Member (Uncredited) |
| Harry Mayo als Audience Member (Uncredited) |
 | Richard Neill als Audience Member (Uncredited) |
 | Eric Mayne als Audience Member (Uncredited) |
| Barry Regan als Audience Member (Uncredited) |
| Edward Locke | Theatre Play |
| Lynn Starling | Screenplay |
| George Waggner | Director |
| Curt Siodmak | Adaptation |
| Curt Siodmak | Screenplay |
| Russell A. Gausman | Set Decoration |
| W. Howard Greene | Director of Photography |
| Russell F. Schoengarth | Editor |
| George Waggner | Producer |
| John B. Goodman | Art Direction |
| Ira Webb | Set Decoration |
| Joseph Gershenson | Executive Producer |
| Edward Ward | Original Music Composer |
| Vera West | Costume Design |
| Hal Mohr | Director of Photography |
| Alexander Golitzen | Art Direction |
| Jack Pierce | Makeup Artist |
| Charles S. Gould | Assistant Director |
| Bernard B. Brown | Sound Director |
| William R. Fox | Sound |
| John P. Fulton | Visual Effects |
| Edward Ward | Music Director |
| Harold Zweifel | Orchestrator |
