A number of biographies have been written about Wallace and they are listed below. I highly recommend the one by Peter Raby as it is well researched and beautifully written.
Bryant, William. 2003. Naturalist in the River: The Life and Early Writings of Alfred Russel Wallace. iUniverse.com. 180 pp.
Clements, Harry. 1983. Alfred Russel Wallace: Biologist and Social Reformer. London: Hutchinson. 215 pp.
Fichman, Martin. 1981. Alfred Russel Wallace. Boston: Twayne Publishers. 188 pp.
Fichman, Martin. 2003. An Elusive Victorian: The Evolution of Alfred Russel Wallace. Chicago & London: University of Chicago Press. 382 pp.
Focher, Federico. 2006. L' Uomo che Gettò nel Panico Darwin: La Vita e le Scoperte di Alfred Russel Wallace. Torino: Bollati Boringhieri. 242 pp.
Fonfría, José. 2003. El Explorador de la Evolución: Wallace. Tres Cantos, España: Nivola. 312 pp.
George, Wilma. 1964. Biologist Philosopher; A Study of the Life and Writings of Alfred Russel Wallace. London: Abelard-Schuman. 320 pp.
Hogben, Lancelot T. 1918. Alfred Russel Wallace, The Story of a Great Discoverer. London: Society for Promoting Christian Knowledge (Pioneers of Progress Men of Science series). 64 pp.
Hughes, R. Elwyn. 1997. Alfred Russel Wallace: Gwyddonydd Anwyddonol. Caerdydd: Gwasg Prifysgol Cymru. 208 pp.
Knapp, Sandra. 1999. Footsteps in the Forest: Alfred Russel Wallace in the Amazon. London: Natural History Museum. 90 pp.
Marchant, James. 1916. Alfred Russel Wallace: Letters and Reminiscences. London: Cassell. 2 vols.
Raby, Peter. 2001. Alfred Russel Wallace, A Life. Princeton NJ: Princeton University Press; London: Chatto & Windus. 340 pp.
Shermer, Michael. 2002. In Darwin's Shadow: The Life and Science of Alfred Russel Wallace: A Biographical Study on the Psychology of History. New York: Oxford University Press. 422 pp.
Slotten, Ross A. 2004. The Heretic in Darwin's Court: The Life of Alfred Russel Wallace. New York: Columbia University Press. 602 pp.
Williams-Ellis, Amabel. 1966. Darwin's Moon: A Biography of Alfred Russel Wallace. London & Glasgow: Blackie. 261 pp.
Wilson, John G. 2000. The Forgotten Naturalist: In Search of Alfred Russel Wallace. Melbourne: Australia Scholarly Publishing. 263 pp.