Spencer Leak, Sr. was born April 15, 1937, to pioneering Chicago mortician A.R. Leak, an insurance salesman from Arkansas who opened Unity Funeral Home in Chicago in 1933 and A.R. Leak Funeral Chapels in 1938. Leak and his three brothers grew up near 37th and State Streets. Attending Raymond Elementary School, he graduated from Hyde Park High School in 1956. Leak went on to Wilson Junior College, and graduated from Worsham College of Mortuary Science in 1959.
Serving in the United States Army in 1960, Leak was stationed in West Germany. He was married briefly to R&B singer Mavis Staples, and later became involved in the Civil Rights Movement. In 1964, Leak joined 10,000 activists led by his father and Reverend Clay Evans to protest the racially segregated Oak Woods Cemetery. That same year, A.R. Leak Funeral Home would open its doors to thousands who wanted to view the body of singing legend Sam Cooke. Leak became president and funeral director of Leak and Sons Funeral Chapel in 1970, assuming a major role in running the family business. He returned to school, earning his B.S. degree from Daniel Hale Williams College in 1979 and his M.S. degree in criminal justice from Chicago State University in 1981. Leak then held a series of positions in public service: Consumer Affairs Chief, Illinois Attorney General (1982-1985); Executive Director, Cook County Department of Corrections (1987-1991); Deputy Chief Inspector-General, Illinois Secretary of State (1991-1993); Manager, Illinois Vehicle Services (1993-1999); Deputy Director, District 1, Illinois Department of Corrections (1993-1999); and Commissioner, Illinois Human Rights Commission (1999-present). Since 1993, Leak has served as President and CEO of Leak and Sons Funeral Home. He also coordinates the radio program, It's Time Truth Speaks, on WGCI-FM.
Leak lives in Chicago with his wife, Henrietta Leak, to whom he has been married for several decades; they have three sons.