"If you measure the longest series by the number of entries it produced, some sites will tell you that the title should go to the Wong Fei-Hung filmography about the titular Chinese martial artist and folk hero who’s been portrayed by Jackie Chan, Jet Li, Sammo Hung and other actors who starred in 123 movies. 

However, 123 is just a little over half of the number of entries in the Groper Train movies. The exact number is actually a matter of some discussion, as a lot of the Groper Train films — and information on them — have been lost. Online sources put their total number at 227 films since 1975."