SP4 may refer to:
SP4, an album by Sneaker Pimps Sp4 transcription factor, a human gene Savoia-Pomilio SP.4, a reconnaissance and bomber aircraft built in Italy during the First World War The Saint Patrick's Day Four Service pack 4 in computing Specialist Four (incorrectly called Specialist 4th class), a former enlisted rank of the U.S. Army, now simply Specialist A model of steam toy made by British manufacturer Mamod a 7.62×41mm silent pistol cartridge Surface Pro 4, a laplet by Microsoft