Some actors are know for their roles in a couple big movies like Mark Hamill or Ralph Machio. Others make many movies and have a successful career with a string of blockbusters like Denzel Washington, Tom Cruise, Mel Gibson, or Russell Crowe. The third group are in different category because they have been in an insane amount of movies. Some of these actors like Morgan Freeman seem to be in almost every movie you see.
Below is a list of some of the actors that have been in over 50 movies. I got this data from IMDB as of today's date. I know some of these actors have also worked as directors and producers of movies, but these numbers are just for films they have acted in. The numbers may be slightly skewed since some of the films they are credited for may be TV shows or video games or a guest appearance on the Simpsons, but at least you can get an idea of the scope of work they've been involved in over the years. I did not intend to exclude actresses, so don't take offense If you are looking for Angelina Jolie or Julia Roberts (neither of which have been in over 50 movies). Here are some of the actors who have been in at least 50 movies.
The 50 + Club
The 100 + Club
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Congratulations to Mickey Rooney for being the most prolific actor I could identify. Maybe being a manipulated childhood star does have its rewards after all. I'm sure I have missed some obvious ones so if anyone comes to mind list them in the comment section.