Rav Yekusiel Yehudah Halberstam (January 10, 1905 - June 18, 1994), is better known as the Klausenberger Rebbe. From a young age his diligence and accomplishments in Torah study and his outstanding character marked him for greatness. But it was in the hellfires of Auschwitz, Dachau, and the Warsaw Ghetto that the enormity of the Klausenberger Rebbe's spirit became apparent for all to see. Suffering personal loss, tragedy and brutality that would drive an ordinary person to the depths of despair, the Klausenberger Rebbe soared to immeasurable spiritual heights. Refusing to compromise his observance of mitzvos in even the slightest way, Rav Yekusiel Yehudah Halberstam was a defiant inspiration to his suffering fellow Jews. With the war's end, his spirit unbroken despite his suffering, he inspired his fellow survivors, bringing hope to the hopeless and the light of faith to those whose world had been darkened.
You may be interested in this picture of the Klausenberger Rebbe:
The Klausenberger Rebbe's biography is available from Feldheim.