Koike is a Japanese surname. Notable people with this surname include:
Akihiko Koike, a retired Japanese male race walker
Akiko Koike, a Japanese voice actress
Akira Koike, a Japanese politician
Ayame Koike, a Japanese actress
Eiko Koike, a Japanese idol and actress
Junki Koike, a Japanese football player
Kazuko Koike, a Japanese creative director
Kazumori Koike, a Japanese sprint canoer
Kazuo Koike, a Japanese manga writer, novelist, and entrepreneur
Kensuke Koike, a Japanese contemporary visual artist
Masaaki Koike, a Japanese baseball player
Masakatsu Koike, a Japanese politician
Reizo Koike, a Japanese breaststroke swimmer
Rina Koike, a Japanese idol and actress
Ryohei Koike, a Japanese football player
Shota Koike, a Japanese baseball catcher
Takeshi Koike, a Japanese studio animator, illustrator, and film director
Teppei Koike, a Japanese actor and singer
Toshiki Koike, a Japanese football player
Yui Koike, a Japanese gravure idol and actress
Yuki Koike, a Japanese football player
Yuriko Koike, a Japanese politician
