Rav Eliyahu Eliezer Dessler (1892 - December 30, 1953) was the gaon of mussar in his generation. Rav Dessler was born in 1891 to family rich in Torah and Mussar. As a young boy he learned in the famed Yeshiva of Kelm where he mastered the entire Shas by heart by the age of 17. He also devoted a great deal of time to Sifrei Chasidus. During this period, the leading Mekubal of the generation, Rav Shlomo Elyashiv, better known as the Leshem, wanted to teach Kabbala to Rav Dessler. However, Rav Dessler avoided this opportunity and regretted it for the rest of his life.
In 1947, after many years of Europe, he started his second career as the Mashgiach Ruchni of the Ponevezh Yeshiva in Bnei Brak. It was from this pulpit that his words rang out to the entire Yeshiva world. His talmidim, including Rav Chaim Friedlander and Rav Aryeh Karmel, published a the legendary multi-volume shmuesen of Rav Dessler called Michtav MeiEliyahu.
You may be interested in this picture of Rav Dessler:
Rav Dessler's biography is available from Artscroll.