Most consecutive sci-fi TV episodes ever
Who
Doctor Who
What
694 total number
Where
Not Applicable ()
When
1989

The original run of science-fiction series Doctor Who (BBC, UK) aired 694 episodes consecutively across 26 seasons between 23 November 1963 and 6 December 1989.

In terms of duration, the original run was on air for 26 years 14 days.