(1824-1873) was a Polish painter and political activist.
Born 1824 in Lisew not far from Warsaw, Leon was the son of a small landowner and an eminent freemason Jan Kaplieski. The Kaplieskis were a Frankist family; his grandfather Eliasz Adam Kaplieski was one of the last known Frankists. Leon Kaplieski studied law and philosophy in Warsaw and Wrocław (Breslau). He was engaged in revolutionary underground groups, fled from the part of Poland under Russian rule, was briefly held and interrogated by the Prussian police, and took part in the revolutionary movement in 1848. In the same year Kaplieski emigrated to Paris where he spent most of his remaining years. He took part in Polish emigre political activities, closely connected with the circle of Hotel Lambert and the Czartoryski family, accompanied the Count Witold Czartoryski during his trip to the Balkans and the Near East. Kaplieski also edited the periodical Ephemerides Polonaises. He was married to Helena Hryniewiecka. In 1871 he moved back to Poland, living mostly in Krakew, and died in 1873 in Milosław. He befriended several well-known Polish artists and writers, including Henryk Rodakowski, Jan Matejka, and Cyprian Kamil Norwid.
Kaplieski studied art in Poland and later in Paris. His first known works are copies of paintings by famous Italian artists; later he became known and appreciated for his patriotic historical paintings as Wernyhora (1855). His best works are portraits: of his mother Julia (1860), the writer Bohdan Zaleski (1857), Count Adam Jerzy Czartoryski (about 1860), and an autoportrait as a Templar (about 1872). Many of his paintings and other works have perished or been lost. Mainly influenced by classical Italian art and his contemporary Rodakowski, L.K. continued the tradition of academic painting and had no interest for the emerging modernist tendencies of the mid-nineteenth century. He won some recognition in France, participating in the Paris art salons. L.K. wrote some poems and a short novel Nad Wisłą (On Wisla).