I think it was Alexander (the great) and macedonians who introduced the phalanx formation to the greeks. Of course they could have usen some kind of shieldwall formation earlier. Alexander used the phalanx very effectivily in his campaing against the Persians.
Alexander did not introduce the phalanx to the Greeks, but he did use them better than the Greeks did before his time. Alexander reformed the Phalanx to make it better, and thus beating the Persians was easier.

Sorry, I don't feel like going into detail I'm lazy right now...