Hiroyuki Imaishi (今石 洋之, born October 4, 1971) is a Japanese key animator and anime/anime influenced animation director and one of the co-founders of Trigger. His style is marked by fast and frantic animation combined with elaborate storyboarding and punchy direction. Prior to founding Trigger, he was an animator and director at Gainax.

His series director debut was Tengen Toppa Gurren Lagann (2007). The anime received an Excellence Prize at the 2007 Japan Media Arts Festival, and Imaishi himself received an individual award at the twelfth Animation Kobe Festival. In 2008, the anime received both "best television production" and "best character design" from the Tokyo International Anime Fair. Later he went on to work as director in the 2010 anime series, Panty & Stocking with Garterbelt. His main influence of being an animator and director are Yoshinori Kanada and his works, in which all his anime titles such as Dead Leaves, Gurren Lagann and Panty & Stocking with Garterbelt pay special tributes to him and his art.