Episode Guide
Episodes are listed in original viewing order, with the production order given in brackets. The original UK air date is given after the title.
| Year One | ||||
| 1. | (1.) | Breakaway | (4 September 1965) | 
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| 2. | (9.) | Force of Life | (11 September 1975) |
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| 3. | (13.) | Collision Course | (18 September 1975) |
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| 4. | (17.) | War Games | (25 September 1975) |
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| 5. | (14.) | Death's Other Domain | (2 October 1975) |
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| 6. | (12.) | Voyager's Return | (9 October 1975) |
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| 7. | (10.) | Alpha Child | (16 October 1975) |
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| 8. | (23.) | Dragon's Domain | (23 October 1975) |
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| 9. | (22.) | Mission of the Darians | (30 October 1975) |
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| 10. | (3.) | The Black Sun | (6 November 1975) |
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| 11. | (8.) | Guardian of Piri | (13 November 1975) |
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| 12. | (16.) | End of Eternity | (20 November 1975) |
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| 13. | (2.) | Matter of Life and Death | (27 November 1975) |
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| 14. | (5.) | Earthbound | (4 December 1975) |
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| 15. | (15.) | The Full Circle | (11 December 1975) |
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| 16. | (6.) | Another Time, Another Place | (18 December 1975) |
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| 17. | (11.) | The Last Sunset | (1 January 1976) |
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| 18. | (19.) | The Troubled Spirit | (5 January 1976) |
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| 19. | (21.) | The Infernal Machine | (8 January 1976) |
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| 20. | (4.) | Ring Around the Moon | (15 January 1976) |
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| 21. | (7.) | Missing Link | (22 January 1976) |
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| 22. | (20.) | Space Brain | (29 January 1976) |
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| 23. | (24.) | The Testament of Arkadia | (12 February 1976) |
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| 24. | (18.) | The Last Enemy | (19 February 1976) |
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| Year Two | ||||
| 1. | (1.) | The Metamorph | (4 September 1976) |
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| 2. | (2.) | The Exiles | (11 September 1976) |
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| 3. | (5.) | Journey to Where | (18 September 1976) |
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| 4. | (3.) | One Moment of Humanity | (25 September 1976) |
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| 5. | (9.) | Brian the Brain | (2 October 1976) |
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| 6. | (12.) | New Adam, New Eve | (9 October 1976) |
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| 7. | (8.) | The Mark of Archanon | (16 October 1976) |
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| 8. | (7.) | The Rules of Luton | (21 October 1976) |
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| 9. | (4.) | All That Glisters | (28 October 1976) |
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| 10. | (6.) | The Taybor | (4 November 1976) |
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| 11. | (13.) | Seed of Destruction | (11 November 1976) |
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| 12. | (12.) | The A-B Chrysalis | (18 November 1976) |
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| 13. | (11.) | The Catacombs of the Moon | (25 November 1976) |
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| 14. | (15.) | Space Warp | (2 December 1976) |
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| 15. | (16.) | A Matter of Balance | (9 December 1976) |
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| 16. | (14.) | The Beta Cloud | (16 December 1976) |
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| 17. | (19.) | The Lambda Factor | (23 December 1976) |
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| 18 | (17.) | The Bringers of Wonder (part 1) | (4 August 1977) |
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| 19. | (18.) | The Bringers of Wonder (part 2) | (11 August 1977) |
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| 20. | (20.) | The Seance Spectre | (18 August 1977) |
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| 21. | (21.) | Dorzac | (25 August 1977) |
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| 22. | (22.) | Devil's Planet | (1 September 1977) |
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| 23. | (23.) | The Immunity Syndrome | (29 October 1977) |
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| 24. | (24.) | The Dorcans | (12 November 1977) |
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