While the Governor of the Massachusetts Bay Colony, John Endicott, was responsible for the execution order, it was the entire colony's government** who was responsible for the silencing of Mary Dyer.
Here's why:
* Quaker beliefs were seen as a threat: The Puritan leaders of the Massachusetts Bay Colony saw Quakerism as a dangerous heresy, particularly their beliefs in inner light, equality, and rejection of established authority.
* Laws were enacted against Quakers: To suppress the spread of Quakerism, the colony passed a series of laws that banished Quakers from the colony and even sentenced them to death if they returned.
* Dyer refused to obey: Mary Dyer, a devout Quaker, returned to the colony despite these laws. She saw it as her duty to share her faith, even at the cost of her life.
* The court sentenced Dyer to death: The Massachusetts Bay Colony court, acting in accordance with its own laws, found Mary Dyer guilty of defying the law and sentenced her to death.
Therefore, it wasn't just a single individual, but the entire government and legal system of the Massachusetts Bay Colony who was responsible for the silencing of Mary Dyer. They believed, at the time, that they were protecting their religious and political system by suppressing Quakerism, even through the use of violence.