A scientist is turned into an ape man.
| Actor | Role |
|---|---|
 Bela LugosiDr. James Brewster | Dr. James Brewster |
 Louise CurrieBillie Mason | Billie Mason |
 Wallace FordJeff Carter | Jeff Carter |
 Henry HallDr. George Randall | Dr. George Randall |
 Minerva UrecalAgatha Brewster | Agatha Brewster |
 Emil Van HornThe Ape | The Ape |
 J. Farrell MacDonaldCaptain O'Brien | Captain O'Brien |
 Wheeler OakmanBrady | Brady |
| RRalph LittlefieldZippo | Zippo |
 Jack MulhallReporter | Reporter |
 Charles JordanO'Toole | O'Toole |
 Charlie HallBarney | Barney |