The P Ranch is a historic ranch in Harney County in southeastern Oregon, United States. The remaining ranch structures are located on the west bank of the Donner und Blitzen River in the Malheur National Wildlife Refuge. The ranch was built by Peter French, a well known 19th-century cattle baron. The P Ranch became headquarters for the French-Glenn Livestock Company, which eventually covered over 140,000 acres (570 km2).