The show that created anime fandom?
The english dub edit of the series known as Star Blazers made a massive impact on US sci-fi fandom in 1979. While there had been other anime shows broadcast, Yamato even in it's toned down form offered a much more sophisticated plot than it's peers. Plus it came along in the midst of Star Wars' popularity (which it was mistakenly accused of ripping off despite being made 3 years before the first SW film), so the appetite of epic space opera was high.
The series arguably created anime fandom in Japan too. A comparative flop as TV series, the show inspired enough passion among those who loved the show to make a success of a compilation movie, which then led to the revitalisation of the series. And the very existance of anime magazines is in part due to Yamato, with Animage launching in the wake of the Yamato movie's success.
The first series of Yamato involves the war between Earth and the Gamilas. Earth converts the battleship Yamato into a spaceship armed with a Wave Motion Gun, and it heads off to the alien world of Iscander to recover a device to cleanse the radiation the Gamilas have poisoned Earth with.
Yamato was created by Yoshinobu Nishizaki, but the person it is mostly associated with is Leiji Matsumoto. It is due to Matsumoto's direction and design that the show had the impact it had, and is so well remembered. Nishizaki and Matsumoto had a legal falling out in the nineties, giving Nishizaki the rights to the names and plot of the series, but Matsumoto the rights to the designs and art.
People who complain about Matsumoto's character designs looking “old” are idiots. Because his character designs haven't really changed and nobody else draws characters like him unless in deliberate homage/parody. He has such an idiosyncratic style that you'd be a fool to rip him off. He's also a really good example of the sort of auteur missing from anime nowadays. People like Matsumoto, Tezuka, Nagai and Ishikawa were able to stand with one foot in manga and one foot in anime and produce series that were very much a personal vision. Nowadays you are hard pressed to think of any equivalents.