686 may refer to:

686, year 686 AD 686 BC 686 (number) 686 Gersuind, a minor planet orbiting the Sun 6-8-6, a wheel arrangement of steam locomotives +686, the country calling code for telephone numbers in Kiribati Gliese 686, a star in the constellation of Hercules Hawaii SB 686, a bill pertaining to cannabis legalization (2019) i686, the P6 (sixth-generation) Intel x86 microarchitecture, implemented in the Pentium Pro microprocessor (1995) K686, pennant number of Royal Canadian Navy ship HMCS Fergus (1944–1945) Kosmos 686, a Soviet satellite launched in 1974 Minuscule 686, a Greek minuscule manuscript of the New Testament Scandinavian Airlines Flight 686, an airplane involved in the 2001 Linate Airport runway collision Smith & Wesson Model 686, a revolver United Nations Security Council Resolution 686, adopted in March 1991 pertaining to Iraq USS Eugene E. Elmore (DE-686), a destroyer escort of the United States Navy (1944–1946) USS Halsey Powell (DD-686), a destroyer of the United States Navy (1943–1968) USS L. Mendel Rivers (SSN-686), an attack submarine of the United States Navy (1975–2001) USS Vester (SP-686), a patrol vessel and minesweeper of the United States Navy (1917–1919) VLY-686, an experimental drug known as tradipitant

See also List of highways numbered 686