The Castro regime, specifically Fidel, for the numerous assassination attempts on him. The Kennedy brothers were absolutely determined to eliminate Fidel because of the humiliation of the Bay of Pigs. This was a personal issue to the Kennedy brothers as no one got away with beating let alone ket alone humiliating a Kennedy. There were several real ambuscade shoot out type attempts on Castro, which leaked into the press at the time but have never appeared in later print accounts. Castro, tyrant he is, had a valid feeling is was either that he eliminated JFK or JFK would eliminate him.
So called organized crime or specifically the ‘west side outfit’ from Chicago.
Joseph Kennedy, Sr. Had made a deal with these people before the 1960 election that in return for their complete support in producing the vote in Chicago there would be no undue federal criminal investigatory activities. Unfortunately JSK, Sr suffered a massive incapacitating stroke in Dec 1961 and there was no one to effectively reign in RFK’s anti-racketeering crusade vis-a-vis the Chicago gangsters. To men such as Sam Giancana it was felt they had been double crossed. There is only one way to respond. Strike at the head if the family that had betrayed them, i.e. JFK.
Third is the Ngo family as payback for the events of 1 Nov 1963 in Saigon.
IMHO, it had deep Masonic roots. Almost any significant power structure could have been involved and most likely played adequate parallel interests where multiple parties were involved. Oswald may have simply been a patsy, but a very knowledgeable, willing, and plausible patsy.
Whomever was involved, I perceived part of LBJ’s depression after his first term may have been subsequent to recognizing the limits of his power to control such a beast.
“Third is the Ngo family as payback for the events of 1 Nov 1963 in Saigon”
Of course there was very little Ngo family left by the end of the month. It wasn’t just Diem who was murdered but his family as well. A Medieval thought which I’ll admit to harboring is that JFK’s death was divine retribution for his role in the murder of Diem and his family. Frederick Nolting was outraged by our role in Diem’s death.
That 1963 coup was one of our stupidest moments. It left Vietnam rudderless for years, Ho Chi Minh could barely believe his good fortune. Lyndon Johnson inherited an out of control South Vietnam and this led to his decision to send in US combat troops, opening an entirely new problem.