The Zombie as we have come to know and love them is Romero's creation (though he cheerfully admits he borrowed the apocalypse angle from Richard Mathieson's novel "I Am Legend". He has had a massive impact on popular culture.
But he did not make only Zombie films. Try "Knightriders" for a different Romeo...though the story is still set in his beloved Pennslyvania.
Telika: I'd say this guy has been more influential on pop culture than a George Lucas, but less widely recognised for it.
tinyE: And his social commentary is timeless.
Romero made a lot of bold statements with his movies during some very troubled times in this country's history, and more than that, they were subtle. He made some very cutting remarks without beating people over the head with them.
Sadly, when he returned to thr Zombie film in the mid 2000's with "Land of the Dead" he did beat people over the head with his message..and, surprise, it is much less effective then the satire in his earlier films.