Abstract: A tamper resistant valve actuator for a fire hydrant has a bullet shaped nose presenting a nongrippable conical surface. Three equally spaced shallow recesses are provided in the conical surface at a common elevation. A special wrench includes radially projecting set screws adapted for complementary fit within the recesses and adjustable tightening thereto for operating the valve stem. The actuator is designed for installation on conventional hydrant assemblies and in substitution of the existing pentagon head operating nut. In a modified embodiment, the valve operating nut is provided with a valve stem socket for compatibility with another form of hydrant assembly. In addition, the wrench receiving recesses are placed in a variant pattern.