If we are talking about influence, Pac-Man, Mario, Donkey Kong and a Space Invader. If there were five I would add Sonic or Link. I would argue there is at least a strong possibility Mario and the like influenced FIFA as without Mario, there may not be a FIFA or the developers involved may have never been interested in programming video games.
If we are talking about personal favorites it woulr be Mario, Link, Samus and Sonic.
If we are talking about series rather than characters it would be Mario Platformers, Legend of Zelda, Street Fighter and Halo.
For people who influenced the industry I would go with Nolan Bushnell(Atari), Shigeru Miyamoto(Mario, Donkey Kong, Link), John Carmack(DOOM and the FPS genre, I know he didn't invent it) and Will Wright(Sims, Sim City, simulations games).
There are a thousand ways to come up with this so no answer is really wrong.
