Officially known as the President's Commission of the Assassination of President Kennedy. It's more common name is the Warren Commission, named after it's chairman, then Chief Justice of the United States, Earl Warren. It's members - Representative Hale Boggs, Senator John Sherman Cooper, Former CIA Director Allen Dulles, Representative Gerald Ford, Former World Bank president and diplomat John J. McCloy and Senator Richard Russell, Jr. - concluded that Lee Harvey Oswald was indeed the sole assassin of John F Kennedy. The Warren Commission is alleged to have ignored witnesses that contradicted this claim, falsifing evidence to fit their theory, and some would say bending the laws of physics with their 'magic bullet" theory.
Popular opinion of this committee is wildly pessimistic, with a great percentage of Americans not believing the "official explanation". Subsequent (government) investigations, such as the 1978 House Select Committee on Assassinations, concluded that Kennedy's assassination was most likely to have been a result of a conspiracy.