Peter IV (in Bulgarian Petăr IV, or commonly but less accurately Petăr II; Bulgarian: Петър IV) ruled as emperor (tsar) of Bulgaria 1185 - 1197. Together with his brother Asen he managed to restore the Bulgarian Empire after nearly 170 years of Byzantine domination.
Before being proclaimed emperor in 1185, Petar IV was named Theodore (Todor). The change of name indicates an attempt to seek legitimacy through a connection with the sainted Emperor Petar I of Bulgaria, whose name was also adopted by earlier rebels against Byzantine rule in 1040 and 1072. The name appears augmented as Slavopetăr ("glorious Petar") and Kalopetăr ("good Petar") in some sources.