Pēteris Krastiņš (1882, Valmiera District – 1942, Riga) was a Latvian painter.
Pēteris Krastiņš came from a peasant family from northern Latvia (at the time part of the Russian Empire).
After his studies he traveled widely across Europe, partially funded by a scholarship, and visited Berlin, Dresden, Vienna, Paris, Florence and Rome in order to study the art and architecture of these well-known artistic destinations.
He stayed for a prolonged time in Florence, sharing accommodation with the Italian artist Filippo Marfori Savini, to whom he had been introduced by his countryman Teodors Zaļkalns.
His mental health had however already begun to deteriorate and at the outbreak of World War I, he was taken in at a mental hospital in Riga, and would stay there until 1942, when he was killed by the Nazis during the German occupation of Latvia during World War II.