ancient Roman (Roman law) prosecutor or informer. The role of the informer in matters of criminal law and fiscal claims was of singular importance to the maintenance of order in Roman society, which was without an adequate police force or public prosecutor. Rewards ranged from pecuniary awards and public praise for citizens to freedom for slaves and citizenship for foreigners.

Delation under the empire consequently became a lucrative, though disreputable, profession. Abusers were punishable by infamia (infamy) (loss of many civil rights), branding, flogging, or banishment. Because their activities could be of singular utility to the emperor, especially one who was untrusting of his subordinates or in need of funds, some unscrupulous delators escaped punishment and even acquired political power.