123

123 may refer to:
 * The first three positive Arabic numerals
 * 123 (number), the natural number following 122 and preceding 124
 * AD 123, a year of the Julian calendar, in the second century AD
 * 123 BC, a year of the pre-Julian Roman calendar
 * 123 Brunhild, a main-belt asteroid

Entertainment

 * 123 (film), a 2002 Indian romantic comedy
 * 123, 2016 Philippines film by Carlo Obispo at 12th Cinemalaya Independent Film Festival
 * "123" (Nikki Laoye song), 2012
 * "123" (Smokepurpp and Murda Beatz song), 2018
 * "123", a song by Jess Glynne from the 2018 album Always In Between

Other

 * 123 (file format), used by the Lotus 1-2-3 spreadsheet program
 * IRT Seventh Avenue Line, served by the 1, 2, 3 New York Subway services
 * 123 (interbank network), a shared cash network in Egypt
 * Japan Airlines Flight 123, which crashed in 1985 near Tokyo