2 Answers

I'm looking for the answer to your question, but this is an interesting article for the time being.

http://www.toptenz.net/top-10-most-successful-actors-at-the-box-office.php    

THIS is what I got from "Ask Yahoo"

To find your answer, we headed straight to the Internet Movie Database (IMDB), a huge and comprehensive film resource we've consulted many times.
First, we looked up Gene Hackman to see if your suspicion was correct. This venerable actor has completed 73 films (not including TV movies) plus one currently in post-production and two uncredited film appearances. That's a respectable number, but it didn't sound record-breaking.

If you're looking for the actor who had the most leading roles in films, Guinness World Records lists John Wayne as tops. The Duke was the leading man in 142 movies.

However, film roles can take many forms, and a voice may be just as important as a face on the screen. The man behind Bugs Bunny and Porky Pig had more movie actor credits to his name than anyone. Mel Blanc performed in 709 films, not including over 100 TV movies and video productions. He also had 81 uncredited voice parts in films.

Of course, these stats only focus on American and European movies. There's a great, big world of filmmaking out there, and India's Bollywood film industry is the most productive on the planet. India made a record of 948 movies in just one year, 1990, and Indian actors regularly make more movies than Hollywood actors.

Right behind Mel Blanc on the IMDB's list of most prolific actors is Adoor Bhasi . Before his death in 1990, Bhasi was featured in 549 films. It's possible that other Indian film actors have been in upwards of 1,000 films, and with Bollywood production steaming along, Bhasi's ranking may be easily surpassed.

I believe Barbra Streisand.