Most TV spin-off series
Who
Ultraman
Where
Japan (Tokyo)
When

The most TV spin-off series is 33, based on the original Ultraman (Japan) TV series, as of 14 July 2015.

The original Ultraman TV series were aired between 17 July 1966 and 9 April 1967. The latest TV spin-off series called Ultraman X first appeared on air on 14 July 2015.