Petru Cazacu (October 6, 1873 in Chişinău – August 1956 in Bucharest) was a doctor of medicine, historian, journalist and politician from Bessarabia.
He served as the prime minister of the Moldavian Democratic Republic in 1918. He is the Grandfather of Loredana Cazacu.
- P. Cazacu, Moldova dintre Prut şi Nistru. 1812–1918, Chişinău, 1992.