| 角色 | 演員 | 備註 |
| Lt. Terry Kent | Ralph Byrd |
|
| Boroff, alias M.A. Anderson | 貝拉·盧戈西（Bela Lugosi） |
|
| Jean Norman | Maxine Doyle |
|
| Thorg | Richard Alexander |
|
| Snapper McGee | Lee Ford |
|
| Cmdr. Boyle | Herbert Rawlinson |
|
| G.A. Rackerby | John Picorri |
|
| Rabinisi (Boroff's spokesman at screening) | 勞倫斯·格蘭特（Lawrence Grant） |
|
| Ens. Jim Kent | 托馬斯·卡爾（Thomas Carr） |
|
| Henchman Dodds [Ch. 4] | Carleton Young |
|
| Dick Norman | Allen Connor |
|
| L.H. DeGado (chief thug) | George Chesebro |
|
| Wies (ambulance orderly thug) | Ranny Weeks |
|
| Goebel, Henchman [Chs. 2, 10] (uncredited) | 羅伊·巴克羅夫特（Roy Barcroft） |
|
| Kelp Plant heavy [Chs. 8-9] (uncredited) | Earle D. Bunn |
|
| (uncredited) | 亞基馬·坎納特（Yakima Canutt） |
|
| Patrol Boat Capt. Johnson [Chs. 1-3, 5, 12] (uncredited) | Ed Cassidy |
|
| Carver (uncredited) | Jack Clifford |
|
| Motorcycle heavy [Ch. 8] (uncredited) | Floyd Criswell |
|
| Captain of the S.S. 'Carfax' [Ch. 1] (uncredited) | Jack Daley |
|
| (uncredited) | Leon Davidson |
|
| Sea Wolf thug [Ch. 7] (uncredited) | Forrest Dillon |
|
| Hospital radium tech [Ch. 11] (uncredited) | Lester Dorr |
|
| Dock heavy [Chs. 6-7, 10] (uncredited) | Curley Dresden |
|
| Pierport station agent [Ch. 6] (uncredited) | Robert Dudley |
|
| Kelp Plant worker [Ch. 8] (uncredited) | Frank Ellis |
|
| Roadside police sergeant [Ch. 3] (uncredited) | Frank Fanning |
|
| Sea Wolf thug [Chs. 3, 5, 7] (uncredited) | Jerry Frank |
|
| Citizen [Ch. 3] (uncredited) | Lee Frederick |
|
| Phone switchboard supervisor [Ch. 2] (uncredited) | Audrey Gaye |
|
| Cmdr. Green [Ch. 1] (uncredited) | Joseph W. Girard |
|
| Kelp Plant heavy [Chs. 8-9] (uncredited) | Kit Guard |
|
| Krohn (Morovanian scientist) (uncredited) | Henry Hale |
|
| Seaman [Chs. 2-3, 6-7] (uncredited) | Jack Ingram |
|
| Boat heavy #4 [Ch. 5] (uncredited) | Warren Jackson |
|
| Coast Guard orderly [Chs. 1, 3] (uncredited) | Rex Lease |
|
| Froman, Morovanian emissary [Ch. 1] (uncredited) | Alexander Leftwich |
|
| Captain of the S.S. 'Adamic' [Ch. 3] (uncredited) | Joe Mack |
|
| Blake (uncredited) | Gene Marvey |
|
| Sniper [Ch. 7-8] (uncredited) | Frankie Marvin |
|
| Policeman [Ch. 6] (uncredited) | Frank Meredith |
|
| Dock heavy [Chs. 6-7, 10] (uncredited) | James Millican |
|
| Radioman (uncredited) | Pat Mitchell |
|
| Ambulance driver-thug [Ch. 3] (uncredited) | King Mojave |
|
| Dr. Meade [Chs. 6, 11] (uncredited) | Edwin Mordant |
|
| Coast Guardsman Moore [Chs. 3, 11-12] (uncredited) | Michael Morgan |
|
| Dock heavy [Chs. 6-7, 10] (uncredited) | Henry Morris |
|
| Coast Guardsman Blake (uncredited) | George Morvey |
|
| S. S. 'Adamic' Mate [Chs. 5-6] (uncredited) | Charles B. Murphy |
|
| Policeman (uncredited) | John Mustin |
|
| Mate on the S.S. 'Carfax' [Ch. 1] (uncredited) | Henry Otho |
|
| Boat heavy [Ch. 5] (uncredited) | Eddie Phillips |
|
| Pete, Thug [Chs. 5, 8] (uncredited) | Loren Riebe |
|
| Dock heavy [Ch. 6-7, 10] (uncredited) | Vinegar Roan |
|
| Jones, Racherby's lab assistant [Ch. 2] (uncredited) | Jack Roberts |
|
| Patrol Boat Lt. Scott (uncredited) | Buddy Roosevelt |
|
| Gang launch pilot [Ch. 1] (uncredited) | Dick Scott |
|
| Thug loading launch [Ch. 11] (uncredited) | Reed Sheffield |
|
| Ambulance attendant-thug [Ch. 3] (uncredited) | Dick Sheldon |
|
| Phone company code expert [Ch. 2] (uncredited) | Harry Strang |
|
| Loader [Ch. 6] (uncredited) | Duke Taylor |
|
| Charlie, 'Sea Wolf' cook [Ch. 7] (uncredited) | Tom Ung |
|
| Phone operator [Ch. 2] (uncredited) | Billie Van Every |
|
| Black (a thug) (uncredited) | Robert Walker |
|
| Henchman Payne [Chs. 3, 5, 7-8, 10-11] (uncredited) | Frank Wayne |
|
| Belden, Cargo Clerk-Thug [Ch. 5] (uncredited) | Herbert Weber |
|
| Sloan, Henchman [Ch. 8] (uncredited) | Robert Williams |
|
| Black, a Thug [Chs. 6-7, 10] (uncredited) | Roger Williams |
|
| Sea Wolf Captain Slauson [Ch. 7] (uncredited) | Dan Wolheim |
|
| Sea heavy #1 [Ch. 5] (uncredited) | Duke York |
|
