Wikipedia has a list that enumerates inventors with 200 or more utility patents. Nobody doubts they are the top prolific inventors in the world.
Some companies, like IBM, recognize their brightest employees when they surpass the 100 patent threshold (like the "100th Invention Plateau Award" in IBM).
However, such quantity of patents per inventor is extremely rare in some developed countries.
For example, in Spain, only 25 people had more than 100 patents 3 years ago, and a 75% of them are inventors from other countries that have extended their patents to all Europe.
Some private LinkedIn groups, like Prolific Inventors Group, have stablished a 25 US granted patent criteria to join its community.
In fact, the term "prolific inventor" is widely used by people with a significant lower number of granted patents. For example, a simple search in LinkedIn reveals lots of professional profiles that use this label in its title, even when they only have 5 or less listed patents (some examples: P. Pharkya, R.Scott, M.D.Grissom,...).
On other hand, some of the Edison patents (and other eminent past prolific inventors) would not have been granted with actual criteria of novelty and inventive step. The patent system has changed a lot in the US and Europe over time. Its evolution tends towards an increasingly strict examination in novelty, while there are more and more possible references that undermine the requirement of inventive step.
I would like to know, when a person is considered a prolific inventor. Is there a common criteria or a number of granted patents that can be used as an standard to distiguish a prolific inventor from other kinds of inventors? Does it vary with country or century? Design patents are also considered?