Depending on how anal you are about "single rotor" The AH-64 Apache has 2 engines and one main rotor. From Wikipedia " American four-blade, twin-turboshaft attack helicopter" https://en.wikipedia.org/wiki/Boeing_AH-64_Apache

Depending on how strict you are about "single rotor" The AH-64 Apache has 2 engines and one main rotor. From Wikipedia "American four-blade, twin-turboshaft attack helicopter"