4, 3, 2, 1 or 4321 may refer to:

• 4.3.2.1., 2010 film by Noel Clarke
• ...4 ..3 ..2 ..1 ...Morte, a 1967 Italian science fiction film

• "4, 3, 2, 1" (k-os song), song by k-os
• "4, 3, 2, 1" (LL Cool J song), song by LL Cool J
• "4-3-2-1", song by Raffi Boghosyan

• 4 3 2 1 (novel), 2017 novel by Paul Auster
• 4–3–2–1, a common formation in association football

• 1234 (disambiguation)
• "5-4-3-2-1", a 1963 single by Manfred Mann
• 54321, a 2016 Tamil thriller film
• Countdown, a sequence of backward counting to indicate the time remaining before an event is scheduled to occur