456 may refer to:

• The year 456 AD
• The year 456 BC
• The year 456 AH in the Islamic calendar
• The British Rail Class 456 electric multiple unit
• The Ferrari 456 road car
• Seong Gi-hun of Squid Game
• The 4, 5, 6 IRT Lexington Avenue Line
• The 456, a race of aliens in the BBC science fiction series Torchwood
• 456 (album), a 1992 album by The Grid
• 4,5,6, a 1995 album by Kool G Rap
• "4, 5, 6", a 1999 song by Solé
• Cee-lo, a dice game also known as Four-Five-Six