Eighteen or 18 may refer to:

• 18 (number)
• One of the years 18 BC, AD 18, 1918, 2018

• 18 (film), a 1993 Taiwanese experimental film based on the short story God's Dice
• Eighteen (film), a 2005 Canadian dramatic feature film
• 18 (British Board of Film Classification), a film rating in the United Kingdom, also used in Ireland by the Irish Film Classification Office
• 18 (Dragon Ball), a character in the Dragon Ball franchise
• "Eighteen", a 2006 episode of the animated television series 12 oz. Mouse

• Argon, a noble gas in the periodic table
• 18 Melpomene, an asteroid in the asteroid belt

• 18 (Moby album), 2002
• 18 (Nana Kitade album), 2005
• 18..., 2009 debut album by G.E.M.
• 18 (Jeff Beck and Johnny Depp album), 2022

• "18" (5 Seconds of Summer song), from their 2014 eponymous debut album
• "18" (One Direction song), from their 2014 studio album Four
• "18", by Anarbor from their 2013 studio album Burnout
• "I'm Eighteen", by Alice Cooper commonly referred to as simply "Eighteen", 1970
• "Eighteen" (CLC song), 2015
• "Eighteen" (Pale Waves song), 2018
• "Eighteen", by Connie Francis, 1957
• "Eighteen", by ¡Forward, Russia!, 2006
• "Eighteen", by Patricia Cahill, B-side to "Colm Bán", 1971

• All pages with titles containing 18
• All pages with titles containing eighteen
• 18 rating (disambiguation)
• 018 (disambiguation) (zero-one-eight)
• o18 (disambiguation) (o-one-eight)
• One8, a lifestyle brand by Indian cricketer Virat Kohli