Yoshiaki Koizumi (born April 29, 1968) is a Japanese video game designer, director and producer, who has been working for Nintendo since 1991.
He originally started working on The Legend of Zelda games:
- A Link to the Past — while originally hired just to provide art and story-text for the manual, Koizumi ended up conceiving much of what became the series' backstory, such as the idea of the three Goddesses and the star sign associated with them.
- Link's Awakening — storyline and characters
- Ocarina of Time — character design, animation and camera. He was in a team of people who invented Z-targeting system which is now a standard for all 3D action games.
- Majora's Mask — characters, storyline and 3-day system
- The Wind Waker — assistant director
He was also working on Mario games, focusing on them full-time after he moved from the Zelda team in late 2002. Every single 3D Mario since Super Mario 64 has him as either director or producer. Most notably, he was the director of Super Mario Galaxy where he snuck in Rosalina's story despite Miyamoto's objection to stories in Mario games. He eventually took over from him as main producer overlooking the mainline 3D Mario series.