Dr. William Pepper (born August 16, 1937) is a barrister in the United Kingdom and admitted to the bar in numerous jurisdictions in the United States of America. His primary work is international commercial law. Pepper has represented governments in the Middle East, Africa, South America, and Asia. Today, Pepper represents Sirhan Sirhan, the gunman convicted in the assassination of Senator Robert F. Kennedy in June 1968.

Pepper was the attorney for James Earl Ray, the convicted killer of Dr. Martin Luther King, Jr., some years after King's death. He believes that Ray was framed by the federal government and that King was killed by a conspiracy that involved the FBI, the CIA, the military, the Memphis police and organized crime figures from New Orleans and Memphis. Pepper, a friend of King in the last year of his life, represented James Earl Ray in a televised mock trial in an attempt to get Ray the trial that he never had.

Pepper then represented the King family in a wrongful death civil trial, King family vs. Loyd Jowers and "other unknown co-conspirators." During a trial that lasted four weeks Pepper produced over seventy witnesses. Jowers, testifying by deposition, stated that James Earl Ray was a scapegoat, and not involved in the assassination. Jowers testified that Memphis police officer Earl Clark fired the fatal shots. 

On December 8, 1999, the Memphis jury found Jowers responsible and found that the assassination plot included also "governmental agencies." The jury took less than an hour to find in favor of the King family for the requested sum of $100.

Pepper is heavily involved in Human Rights Law, for a time convening the International Human Rights Seminar at Oxford University, during which time individuals such as Hugo Chavez, the President ofVenezuela, accepted invitations to address the seminar. He lives primarily in the United States.