Ok1 is the Polish designation of the Prussian P8 steam locomotive used on the Polish State Railways PKP. After the end of World War I, 192 Class P 8 engines were handed over as a reparation to Poland. Since the class was considered successful, further 65 locomotives were built in Germany at Polish order in 1922-1923. During World War II all the locomotives were captured by the Germans or Soviets. After the war, along with new war reparations, Poland received 429 locomotives P 8 (numbers Ok1-1 to 429), what made it by far the most numerous passenger locomotive in the country. They were used until the late 1970s. The last locomotive was withdrawn from active service in 1981. A few engines were preserved, including Ok1-359.