A surgical instrument includes a shaft and a pair of jaw members disposed on the shaft and extending from an at least partially spherical element. The jaw members are moveable in pitch and yaw relative to the center of the sphere in response to actuation forces applied to a proximal drive mechanism of the instrument. The surgical instrument may include a manually operated handle for manual input of actuation forces by a user, or it may be removably mounted to a drive component of a robotic system such that its proximal drive mechanism is operatively engaged with actuators that generate mechanical output that is transferred to the proximal drive mechanism.