Who kills John proctor?

Miller has Mary Warren accusing Proctor of afflicting her but this followed his initial accusation by Abigail in early April 1692. There is no historical evidence to suggest that Abigail even knew John Proctor before she accused him of witchcraft.

John Proctor was killed in the Salem witch trials. He was the first male accused of witchcraft and was hanged, probably by the city's executioners and governors.