A turbocharger includes an annular bypass volute to allow exhaust gas to bypass the turbine wheel. An annular bypass valve is disposed in the bypass volute. The bypass valve comprises a fixed annular valve seat and a rotary annular valve member arranged coaxially with the valve seat. The valve member is disposed against the valve seat and is rotatable about the axis for selectively varying a degree of alignment between respective orifices in the valve seat and valve member. The valve member is rotatably driven by a rotary actuator and drive linkage that rotates about an axis parallel to and offset from the axis about which the valve member rotates.