He died peacefully with his wife, Jay, at his side, a month after he announced he had brain and lung cancer, his family said in a statement.
Stokes was elected to the House in 1968, becoming Ohio's first black member of Congress and one of its most respected and influential.
Just a year earlier, his brother, Carl, had been elected mayor of Cleveland the first black elected mayor of a major US city.
The White House issued a statement from President Barack Obama that noted how Stokes overcame hardships while growing up in Cleveland and praised him for his belief that everyone should have a chance to succeed.
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Stokes headed the House's Select Committee on Assassinations that investigated the slayings of President John F Kennedy and Dr Martin Luther King Jr in the late 1970s and concluded that in both cases, there "probably" had been a conspiracy.
Later, he served on the Iran-Contra investigative committee, where he drew attention with his unflinching interrogation of Lt Col Oliver North.
Stokes was one of the Cold War-era chairmen of the House Intelligence Committee, headed the Congressional Black Caucus and was the first black on the House Appropriations Committee. Stokes' public demeanor was patient and analytical, but colleagues also knew him as tough, principled and skillful.
Stokes served in the Army from 1943 to 1946 in a segregated unit where he said he experienced racism for the first time in his life.
Stationed in Mississippi, he and other blacks were sentenced to the guard house for refusing to pick up papers around the white soldiers' barracks, and once confined, found the guard house had separate toilets for white and black soldiers.