Abstract: A valve actuator assembly is provided for use with a valve body. The valve body includes a valve member for controlling flow of fluid through the valve body, which is mounted to a valve stem having an external connector portion. The valve body includes engagement structure, and the valve actuator is removably engageable with the valve body via a latching member movable into and out of engagement with the engagement structure. The valve body is configured such that a valve actuator providing either normally closed or normally open operation can be mounted to the valve body. The valve actuator includes a motor having an output engageable with a drive gear, which in turn is engageable with the valve stem when the valve actuator is mounted to the valve body. The actuator can be changed from providing normally open operation to providing normal closed operation simply by replacing one drive gear of the valve actuator with another.