This paper addresses imager evolution from the early geostationary imagers to the present and includes changes in requirements which drove instrument development and design. The GOES missions are compare with emphasis on development, performance differences, and design challenges. The imager overview section focuses on the current system design and contains a system description, instrument characteristics, operational performance, a summary of the test program, and the launch schedule. The key instrument design areas discussed are the optical design, scan control and operation, thermal control design, in-flight calibration, and operational data distribution. Technical advancements and differences between the current GOES imager and its immediate predecessors are addressed. Plans for follow-on GOES missions beyond the GOES I-M series, in the context of the evolution of GOES imager instruments, provide a view into technological developments in the near-future.