Joe's suicide run and heroic sacrifice at the end of the first series. At the edge of the death, with just a week of life, Joe goes on a suicide mission to bring down Galactor once and for all. He survives a horrific torture at the hands of Berg Katse and ends up, before dying, throwing his feather knife into the doomsday machine Berg is using to use to destroy the Earth, stopping it right when the countdown reaches his number "2".
ADV Films announcing AND releasing ALL 105 episodes also counts, given the fact that countless fans were fearful that the company would abort the project before it reached the final 20 episodes, which had never ever been dubbed before.
Sentai Filmworks (ADV's successor) managing to rescue the license to the original Gatchaman in 2013, and even redubbing the OVA series.