Publius (or Gaius) Cornelius Tacitus (ca. AD 56 – ca. AD 120) was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors. These two works span the history of the Roman Empire from the death of Augustus in AD 14 to the years of the First Jewish–Roman War, in 70 AD. There are enormous lacunae in the surviving texts, including one four books long in the Annals.

Other works by Tacitus discuss oratory (in dialogue format, see Dialogus de oratoribus), Germania (in De origine et situ Germanorum), and biographical notes about his father-in-law Agricola, primarily during his campaign in Britannia (see De vita et moribus Iulii Agricolae).

Tacitus was an author writing in the latter part of the Silver Age of Latin literature.