Father Walter Ciszek, S.J. (1904-1984)

Rev. Walter Ciszek, S.J. was a Polish-American Jesuit priest known for his clandestine missionary work in the Soviet Union between 1939 and 1963. Fifteen of these years were spent in confinement and hard labor in the GULAG, including five in Moscow‘s infamous Lubyanka prison. He was released and returned to the United States in 1963, after which he wrote two books, including the memoir With God in Russia, and served as a spiritual director. Since 1990, Ciszek has been under investigation by the Roman Catholic Church for possible beatification or canonization. His current title is a Servant of God. For more on Ciszek check out this Youtube clip:

(From Wikipedia)