Lucius Appuleius Saturninus (died late 100 BC) was a Roman populist and tribune. He is most notable for introducing a series of legislative reforms, alongside his associate Gaius Servilius Glaucia and with the consent of Gaius Marius, during the last years of the second century BC. Senatorial opposition to these laws eventually led to an internal crisis, the declaration of the senatus consultum ultimum, and the deaths of Saturninus, Glaucia, and their followers in 100 BC.