Mark Harris / Billy Jones (17 episodes, 1977-1978)
C.W. Crawford (16 episodes, 1977-1978)
Dr. Elizabeth Merrill (15 episodes, 1977-1978)
Cetacean crew (11 episodes, 1977-1978)
Cetacean crew (9 episodes, 1977-1978)
Mr. Schubert (6 episodes, 1977)
Cetacean crew (6 episodes, 1977-1978)
Brent (4 episodes, 1977)
Cetacean crew / Air Lock Man / Popeye (3 episodes, 1977)
Dr. Miller Simon (3 episodes, 1977)
Jack Muldoon (2 episodes, 1977-1978)
Captain Bracy (2 episodes, 1977)
Jane / Sara (2 episodes, 1977)
Cetacean crew (2 episodes, 1977)
Stringer (1 episode, 1977)
Ernie Smith (1 episode, 1977)
Charlene Baker (1 episode, 1978)
Juliet (1 episode, 1977)
Belle (1 episode, 1977)
Clint Hollister (1 episode, 1977)
Amanda Trevanian (1 episode, 1977)
Adm. Dewey Pierce (1 episode, 1977)
Moxie (1 episode, 1978)
Duke (1 episode, 1978)
Havergal (1 episode, 1977)
Dr. Mary Smith (1 episode, 1977)
Dilly / Lioa (1 episode, 1977)
Thark (1 episode, 1977)
Romeo (1 episode, 1977)
Lew (1 episode, 1977)
Bettina Washburn (1 episode, 1977)
Hugh Trevanian (1 episode, 1977)
Moby (1 episode, 1978)
Canja (1 episode, 1978)
Summersday (1 episode, 1978)
Artemus Washburn (1 episode, 1977)
Smith (1 episode, 1977)
Cmdr. Phil Roth (1 episode, 1977)
Ginny Mendoza (1 episode, 1977)
Chazz / Xos (1 episode, 1977)
Dashki (1 episode, 1977)
Louisa (1 episode, 1977)
Dick Stoneman (1 episode, 1977)
Jenny Reynolds (1 episode, 1977)
Sid (1 episode, 1977)
Encyclopedia salesman (1 episode, 1977)
Trubshawe (1 episode, 1977)
Click One (1 episode, 1977)
Officer (1 episode, 1978)
Oscar (1 episode, 1978)
(1 episode, 1978)
Carla (1 episode, 1977)
Caine (1 episode, 1977)
Blaise Mullen (1 episode, 1977)
Tybalt (1 episode, 1977)
Pamela (1 episode, 1977)
Lt. Ainsley (1 episode, 1977)
Boy (1 episode, 1977)
Cab Driver (1 episode, 1977)
(1 episode, 1977)
Juliette Schubert (1 episode, 1977)
Click Two (1 episode, 1977)
Trivi (1 episode, 1978)
Bert Davis (1 episode, 1978)
Friar Laurence (1 episode, 1977)
Virgil (1 episode, 1977)
Doctor (1 episode, 1977)
Bartender (1 episode, 1977)
Maitre'D (1 episode, 1977)
Vicki (1 episode, 1977)
Click Three (1 episode, 1977)
Edwin Shirley (1 episode, 1977)
Grant Stockwood (1 episode, 1977)
Siren (1 episode, 1977)
Clavius (1 episode, 1978)
Student (1 episode, 1978)
Toba (1 episode, 1978)
Colonel Manzone (1 episode, 1977)
FBI Agent Fuller (1 episode, 1977)
Dr. Doug Berkley (1 episode, 1977)
Maitre D' (1 episode, 1977)
Policeman (1 episode, 1977)
Mercutio (1 episode, 1977)
Buddy O'Toole (1 episode, 1978)
Lt. Cmdr. Johnson (1 episode, 1977)
Prince Escalus (1 episode, 1977)
Chauffer (1 episode, 1977)
Cetacean crew (1 episode, 1977)
Sub Captain Wes (1 episode, 1977)
Woman on beach with note (1 episode, 1977)
Guard (1 episode, 1978)
Whale Scientist (1 episode, 1977)
Police Detective (1 episode, 1977)
Sampson (1 episode, 1977)
Medical Examiner (1 episode, 1977)
Woman at Bar (1 episode, 1977)
Man (1 episode, 1978)
Emil (1 episode, 1977)
Security Guard at dock (1 episode, 1977)
Second Officer (1 episode, 1977)
Henchman (1 episode, 1977)
Proprietor (1 episode, 1978)
Minion (1 episode, 1977)
British Scientist (1 episode, 1977)
French Scientist (1 episode, 1977)
Conrad (1 episode, 1977)
Herb Wayland (1 episode, 1977)
Lou (1 episode, 1977)
American Scientist (1 episode, 1977)
Hot Tub Manager (1 episode, 1977)
Russian Scientist (1 episode, 1977)
George (1 episode, 1977)
Myrtle (1 episode, 1977)
Fish Store Clerk (1 episode, 1977)
First Receptionist (1 episode, 1977)
Woman at Party (1 episode, 1977)
Diver (1 episode, 1977)
First Nurse (1 episode, 1977)
Intern (1 episode, 1977)
Man on Beach (1 episode, 1977)
Second Receptionist (1 episode, 1977)
Third Receptionist (1 episode, 1977)
Ambulance Driver (1 episode, 1977)
Test Lab Technician (1 episode, 1977)
Habitat Technician (1 episode, 1977)
Second Nurse (1 episode, 1977)
X-Ray Technician (1 episode, 1977)
Boy on Beach (1 episode, 1977)
Boy at Phone Booth (1 episode, 1977)
Hot Dog Stand Owner (1 episode, 1977)
Sub Navigator (uncredited) (2 episodes, 1977)
Ditcher (uncredited) (1 episode, 1977)
Dr. Medlow (uncredited) (1 episode, 1977)
Newscaster (uncredited) (1 episode, 1977)
Mother (uncredited) (1 episode, 1977)
Bartender (uncredited) (1 episode, 1977)
Hollister's Henchman (uncredited) (1 episode, 1977)
Technician (uncredited) (1 episode, 1977)
Schubert crewman (uncredited) (1 episode, 1977)
Clara (uncredited) (1 episode, 1977)
Constable (uncredited) (1 episode, 1977)
(uncredited) (1 episode, 1978)
Officer (uncredited) (1 episode, 1978)