Air Turbine Starters (ATSs) having oil feed shutoff valves are provided, as are gas turbine engines including ATSs. In one embodiment, the ATS includes an ATS housing assembly containing a sump chamber, an oil inlet, and a valve cavity. A rejected oil return passage is further formed in the ATS housing assembly and fluidly coupled to the valve cavity. An oil feed shutoff valve is positioned in the valve cavity and contains a valve element movable between open and closed positions. In the open position, the valve element permits oil flow from the oil inlet, through the valve cavity, and into the sump chamber. In the closed position, valve element blocks oil flow from the oil inlet into the sump chamber, while redirecting the oil flow into rejected oil return passage to reduce the loss of engine oil through the ATS in the event of an ATS housing breach.