OSU, Osu, or osu can stand for:

• Ohio State University, in Columbus, Ohio, United States
• Oklahoma State University–Stillwater, in Stillwater, Oklahoma, United States
• Oregon State University, in Corvallis, Oregon, United States
• Okayama Shoka University, a Japanese private university in Okayama, Japan

• Osu, Accra, a district in Ghana, West Africa
  • Osu Castle
• Ōsu, a district of Nagoya, central Japan
• Ohio State University Airport (IATA: OSU), Columbus, Ohio, United States

• Osu! Tatakae! Ouendan (series), a series of three rhythm video games for the Nintendo DS console released from 2005 to 2007
  • Osu! Tatakae! Ouendan, a 2005 rhythm game for the Nintendo DS
  • Moero! Nekketsu Rhythm Damashii Osu! Tatakae! Ouendan 2, the game's 2007 sequel
• osu!, a rhythm game first released in 2007 which was inspired by Osu! Tatakae! Ouendan, originally for Windows and later ported to other systems

• Old Salt Union, a newgrass band from Illinois
• Operation Straight Up, an evangelical organization that provided Christian-themed entertainment to the United States military
• Order of St. Ursula, a branch of Ursulines (Roman Catholic Christian religious order)
• Osu caste system, a caste system practiced by the Igbo people in West Africa
• Ottawa South United, a Canadian soccer team

• Ozu (disambiguation)