SL3 may refer to:

Technology and transport Leica SL3, a mirrorless digital camera Canon EOS 250D, or Rebel SL3, a digital reflex camera SL3 (MBTA bus), Boston bus line Skylab 3 (SL-3), a NASA space mission London Buses route SL3

Other uses SL postcode area, the Slough postal region in South East England