In this Dan Curtis production of the Robert Louis Stevenson classic, Jack Palance stars as Dr. Henry Jekyll, a scientist experimenting to reveal the hidden, dark side of man, who, in the process of his experiment, releases a murderer from within himself.
| Actor | Role |
|---|---|
 Jack PalanceDr. Jekyll / Mr.Hyde | Dr. Jekyll / Mr.Hyde |
 Denholm ElliottGeorge Devlin | George Devlin |
 Leo GennDr. Lanyon | Dr. Lanyon |
 Torin ThatcherSir Turnbull | Sir Turnbull |
 Rex SevenoaksDr. Wright | Dr. Wright |
 Gillie FenwickPoole der Butler | Poole der Butler |
| EElizabeth ColeHattie | Hattie |
 Duncan LamontSergt. Grimes | Sergt. Grimes |
| PPaul HardingConstb. Johnston | Constb. Johnston |
 Oskar HomolkaStryker | Stryker |
 Billie WhitelawGwyn Thomas | Gwyn Thomas |
| WWilliam NunnCassidy | Cassidy |
| JJeanette LandisLiz | Liz |
| LLiza CreightonBillie | Billie |