Pitfall for the Atari 5200.  Activision was formed from a team of ex-Atari game designers and programmers, and it was Pitfall that made a household name out of David Crane. David Crane arguably created the first videogame platform hero out of Pitfall Harry, and in this non-scrolling platformer players worked their way through the jungle. Extremely dated by today's standards sure, but back then it was a big deal. You just have to give props to the hero that brought personality to the world of flashing blocks and lines.