Usui (written: 碓井, 碓氷, 臼井, 笛吹 or 卯水) is a Japanese surname. Notable people with the surname include:
Hana Usui (born 1974), Japanese artist
Hideo Usui (born 1939), Japanese politician
Hiroyuki Usui (born 1953), former Japanese football player and manager
Hitoshi Usui (born 1988), Japanese football player
Junichi Usui (born 1957), retired Japanese long jumper
Kaoru Usui (born 1916), photographer
Kempei Usui (born 1987), Japanese footballer
Kohei Usui (born 1979), Japanese football player
Masahiro Usui (born 1991), Japanese actor
Masako Usui (born 1968), Japanese newscaster
Mikao Usui (1865–1926), religious teacher, founder of Reiki
Mikoto Usui
Rie Usui (born 1989), Japanese women's footballer
Usui Sadamitsu, warrior
Yoshimi Usui (1905–1987), Japanese author and critic
Yoshito Usui (1958–2009), Japanese manga artist
As given name:
Usui Kojima (1873–1948), Japanese author
Fictional characters:
Kazuyoshi Usui or Switch, a character in anime and manga series Sket Dance
Horokeu Usui or Horohoro, a character in anime and manga series Shaman King
Uonuma Usui, a character in anime and manga series Rurouni Kenshin
