The present technology relates to an image sensor capable of achieving both higher S/N and higher frame rate, an electronic device, a control device, a control method, and a program.An AD converter has a comparator in which differential pairs are provided at an input stage. The differential pairs have a plurality of transistors as first transistors and second transistors paired to configure the differential pairs. The AD converter compares a level-changing reference signal with an electric signal output by a shooting unit for performing photoelectric conversion and outputting the electric signal, thereby performing AD conversion on the electric signal. The comparator is controlled such that a transistor to be operated is selected as active transistor from among the transistors depending on the amount of light incident in the shooting unit and the active transistor operates. The present technology is applicable to an image sensor for shooting an image, and the like, for example.