George Kennedy. 4 Airport movies and the 3 Naked Gun movies.
Eddie Murphy in Beverly Hills Cop 1 -3 and The Shrek movies if you count animation. Also needs another 48 Hours movie or Nutty Professor and he'll have 3 characters.
Arnold Schwarzenegger. but only if you count the fact that his character in Red Sonya is supposed to be Conan but his name had to be changed to Kalidor for some kind of legal reasons. played Conan and The Terminator.
Michael Caine. Played spy Harry Palmer in at 5 films and will soon play Alfred Pennyworth for a third time.
Jackie Chan. The Rush Hour Films and the first four Police Story films)
Mike Myers. Austin Powers and Shrek. Another Waynes World and he has 3
Michael York. 3 Austin Powers movies and 3 Three/Four Musketeer movies.
Theres's lots of people that are one movie short.
If Bill and Ted III ever gets made you can add Keanu Reeves to the list.
If Christopher Lambert ever does Fortress 3 you can add him to the list.
If Bruce Willis does another Whole Nine Yards sequel you can add him to the list.
If John Travolta ever plays Tony Manero or Chili Palmer again you can add him to the list.
Vin Diesel (Needs another Riddick movie).
Antonio Bandaras (needs another Zorro or El Mariachi movie but he's in if you count Puss N Boots).
These guys are also close but these movies are even less likely to happen.
Sean Connery (Needs another Highlander but theres no way thats going to happen), Chevy Chase (Needs another Fletch), Chuck Norris (Needs another Delta Force), Gene Hackman (needs another French Connection).