Bolesław Bogdan Piasecki (alias Leon Całka, Sablewski; born February 18, 1915 in Łódź, died January 1, 1979 in Warsaw) was a Polish politician and writer.

In interwar Poland he was one of the more prominent nationalist politicians, playing an important role in the leadership of Obóz Narodowo-Radykalny. In 1934 he was interned in Bereza Kartuska. After his release, he became the leader of the illegal, extreme right faction ONR-Falanga. This organisation advocated "Catholic totalitarianism" and is considered by many to have been a fascist movement.

During the Second World War he fought in the Polish Underground, leading the grouping Konfederacja Narodu (merged into the Armia Krajowa in 1943) and taking part in the fighting around Vilnius. Afterwards, he was arrested by the Soviet NKVD, and in a drastic conversion from his previous stance began to cooperate with the Communist government in Poland.

After the war, in 1945, he cofounded and directed a so-called social progressive movement of lay Catholics, grouped around the weekly publication "Dzisiaj i Jutro" (Today and Tomorrow). In 1947 he created the PAX Association and was the chairman of its governing body (until his death). After 1956, the importance of PAX diminished (and Piasecki's role along with it), though it remained a prominent organisation until 1989 and its successors still exist today.

In later years, Piasecki was a member of the Polish Sejm from 1965, where he presided over the grouping of members associated with PAX. In 1971-1979 he was a member of the Polish Council of State.

Honours and awards

• Silver Cross of the Virtuti Militari (1944)
• Commander's Cross with Star of the Order of Polonia Restituta (1964), previously awarded the Commander's Cross (1955)
• Order of the Banner of Work, 1st Class (1969)