Józef Marcinkiewicz (March 30, 1910 in Cimoszka, near Białystok, Poland) – 1940 in Katyn, USSR) was a Polish mathematician.

He was a student of Antoni Zygmund; and later worked with Juliusz Schauder, and Stefan Kaczmarz. He was a professor of the Stefan Batory University in Wilno.

Marcinkiewicz was taken as a Polish POW to a Soviet camp in Starobielsk. The exact place and date of his death remain unknown, but it is believed that he died in the Katyn massacre on the mass murder site near Smolensk. His parents, to whom he gave his manuscripts before the beginning of World War II, were transported to the Soviet Union in 1940 and later died of hunger in a camp.

Their fate is described by Zygmund described the last and his lost mathematical works as follows:

War broke out a few days after Marcinkiewicz returned to Wilno. Zygmund writes On September 2, the second day of the war, I came across him accidentally in the street in Wilno, already in military uniform ... We agreed to meet the same day in the evening but apparently circumstances prevented him from coming since he did not show up at the appointed place. A few months later came the news that he was a prisoner of war and was asking for mathematical books. It seems that this was the last news about Marcinkiewicz. During his time in Paris and England, Marcinkiewicz had produced some mathematical work which he had written down in manuscript form. After returning to Poland he gave these manuscripts to his parents for safe keeping. Sadly Marcinkiewicz's parents suffered the same fate as he did and died during the war. No trace of the manuscripts was ever found.