And unfortunately, he also did drugs, which likely contributed to his early demise in 1977 at age 42. While Elvis's candle may have burned twice as brightly as Chuck Berry's for a time, it also flamed out 40 years earlier.

Although Elvis Presley's music never quite evolved in the 1960s to meet the changing times and tastes of that era, a decision that probably rests with Col. Parker's dubious marketing choices, he certainly lasted a lot longer professionally than did so many of his contemporaries from the late 1950s and early '60s. His last No. 1 record was "Suspicious Minds" in 1969, and last Top 20 hit was "Temperature Rising" in 1972. Had he lived, he'd have likely been playing on nostalgia at Caesar's Palace in his later years.

(Coincidentally, and years after he had reached his peak in popularity, Chuck Berry also enjoyed his only No. 1 hit in 1972, the double entendre-laden "My Ding-a-Ling.")

From Col. Parker's standpoint, Elvis's death was undoubtedly a great career move that cemented his immortality among his legions of fans. But Chuck Berry's legacy as a musician is far more substantive and enduring. For while Elvis first capitalized on rock, Chuck was literally invented the genre and thus influenced several generations of musicians -- including Elvis himself.