Let's see: Guatemala had a dictator, Efrain Rios Monnt.
Costa Rica is a little more complicated, but the government under Rafael Ángel del Socorro Calderón Guardi was repressive too, but in any case, Tinoco Granados was a dictator before that.
Nicaragua had a dictator: Anastasio Somoza
Belize: Belize seems to be the best answer, although it became independent only in 1981.
