Answer:
President Ngo Dinh Diem
Step-by-step explanation:
President Ngo Dinh Diem, who ruled South Vietnam from 1955 to 1963, was a Roman Catholic and faced several religious issues during his presidency.
However, it is important to note that he did not execute a specific religious group in Vietnam. Diem did face criticism for favoring the Catholic minority over the Buddhist majority, which led to tension and protests among the Buddhist population.
The most notable incident was the Buddhist crisis in 1963, where Buddhist monks self-immolated in protest against Diem's policies.
Eventually, the protests and unrest contributed to his downfall in a coup in November 1963.