Final answer:
James Earl Ray was the assassin of Martin Luther King Jr., while other individuals mentioned were responsible for other historical assassinations.
Step-by-step explanation:
The individual who assassinated Martin Luther King Jr. is James Earl Ray. To clarify, Lee Harvey Oswald was involved in the assassination of President JF_K, John Wilkes Booth was the assassin of President Abraham Lincoln, and Sirhan Sirhan assassinated Robert F. Kennedy. The assassination of these prominent figures in American history has led to multiple inquiries and investigations, including the Warren Commission, aiming to reveal the circumstances surrounding these tragic events.