Peter or Nicholas are two names that have been used by Tsars and Czars throughout history. A TSAR or CZAR is a title given to a monarch or emperor in Eastern Europe, Russia, and the former Soviet Union. The term is derived from the Latin word Caesar, which was used to refer to Roman emperors. The title of TSAR or CZAR was used by rulers of the Russian Empire from 1547 until 1917, when the monarchy was abolished. The title was also used by rulers of other countries in Eastern Europe, such as Bulgaria, Serbia, and Romania.