Fine, cui bono?
1. The mob. The Kennedys were after them.
2. The CIA. JFK knew their secrets and wouldn't play ball.
3. J. Edgar. The gig was up.
4. The Commies. Payback for the CMC.
5. Right wing nutjobs. The far right thought Kennedy
was a Commie.
6. The Cubans (either side). Payback for the BoP.
7. Joe Senior's enemies. The most hated man in America had more than his share.
8. LBJ. If you aim for the king, don't miss.
9. China. JFK was famously paranoid about the PRC and might have started a nuclear war.
10. The State Department. See 9.
Have I forgotten anybody? Because... I mean... who
didn't want to kill Kennedy?
Edit: oh, apparently I did forget somebody (the Fed). Never heard that one. Good catch!