 | Charles 'Bud' Tingwell | ... | Capt. Jaffe / ... (3 episodes, 1965-1969) |
| Peter Copley | ... | Charles Wilson / ... (3 episodes, 1965-1971) |
| Geoffrey Palmer | ... | Chief Officer / ... (3 episodes, 1965-1971) |
| Erik Chitty | ... | Bernard / ... (3 episodes, 1965-1969) |
| Ronald Lewis | ... | Dr. Max Harrow / ... (2 episodes, 1965-1966) |
| David Langton | ... | Dr. Morrison / ... (2 episodes, 1965-1966) |
| James Maxwell | ... | Jonas Foster / ... (2 episodes, 1965-1966) |
| Tom Criddle | ... | Doctor / ... (2 episodes, 1965-1966) |
| Keith Buckley | ... | Scotty / ... (2 episodes, 1965-1966) |
| Jessica Dunning | ... | Annika / ... (2 episodes, 1965-1966) |
| Tony Wager | ... | Harvey / ... (2 episodes, 1965-1966) |
| Geoffrey Kenion | ... | Birch / ... (2 episodes, 1965-1966) |
| David Munro | ... | Ken / ... (2 episodes, 1965-1971) |
| Anthony Bate | ... | General / ... (2 episodes, 1966-1971) |
| Tenniel Evans | ... | QT-1 / ... (2 episodes, 1965-1967) |
| Petra Davies | ... | Mary Birkett / ... (2 episodes, 1966-1969) |
| Peter Barkworth | ... | Dr. Philimore / ... (2 episodes, 1969-1971) |
| David Collings | ... | R. Daneel Olivaw / ... (2 episodes, 1966-1969) |
| John Robinson | ... | Dr. Saint / ... (2 episodes, 1966-1969) |
| Robert James | ... | Dr. Kersh / ... (2 episodes, 1965-1969) |
| Peter Madden | ... | Spelman / ... (2 episodes, 1965-1966) |
| Derek Benfield | ... | Dr. Moore / ... (2 episodes, 1969-1971) |
| Clifford Cox | ... | Ewan McKenzie / ... (2 episodes, 1969-1971) |
| Shirley Cain | ... | Frances Mervyn / ... (2 episodes, 1965-1971) |
| Jerry Stovin | ... | Spaceship captain / ... (2 episodes, 1965-1966) |
| Jane Jordan Rogers | ... | Voice of Friend / ... (2 episodes, 1966) |
| David Cargill | ... | Radio man One / ... (2 episodes, 1966-1969) |
| Raymond Hardy | ... | Radio man Two / ... (2 episodes, 1966-1969) |
| Alan Downer | ... | John Sherwood / ... (2 episodes, 1969-1971) |
| Michael Danvers-Walker | ... | Brett / ... (2 episodes, 1965-1966) |
| Sebastian Breaks | ... | Paul Porter / ... (2 episodes, 1966-1971) |
| Wendy Gifford | ... | Dr. Susan Calvin / ... (2 episodes, 1965-1969) |
| Robert MacLeod | ... | American man / ... (2 episodes, 1965-1969) |
| Milo O'Shea | ... | Henry Wilkes / ... (2 episodes, 1965-1969) |
| John Gabriel | ... | Easterbrook / ... (2 episodes, 1965-1966) |
| Patrick Scanlan | ... | Captor / ... (2 episodes, 1965) |
| John Wentworth | ... | Barton / ... (2 episodes, 1966-1971) |
| Barry Warren | ... | Larry Belmont / ... (2 episodes, 1966-1969) |
| Bernard Brown | ... | Frank Bowers-Two / ... (2 episodes, 1969-1971) |
| James Copeland | ... | Oliver MacDonald / ... (2 episodes, 1969-1971) |
| June Ellis | ... | Brenda / ... (2 episodes, 1969-1971) |
| Gerald Sim | ... | Det. Sgt. Greene / ... (2 episodes, 1969-1971) |
| John Berwyn | ... | Japhet / ... (2 episodes, 1969) |
| Steve Peters | ... | Man / ... (2 episodes, 1969) |
