A reflector telescope is an optical telescope that reflects light and structures an image by using a combination of curved and flat (plane) mirrors. The difference between reflector telescopes and others is that they do not use lenses to refract or merge light to form an image. An Italian monk Niccolo Zucchi was the first one to try to create a reflector telescope in 1616 and his is considered to be the inventor of reflector telescopes. But actually he was unable to shape a concave mirror properly and he did not have enough means to view the desirable image without blocking the mirror and soon he gave up the idea of making a reflector telescope. After 54 years a British scientist and inventor Sir Isaac Newton used the very first reflector circa. By inventing and building the circa Newton wanted to solve the problem of chromatic aberration, a serious problem in all reflector telescopes before the flawlessness of achromatic lenses. The common and traditional two- mirrored reflector telescope is widely referred to as the Newtonian reflector.

Newtonian focus plan is still used in amateur astronomy and in the hands of people who investigate the sky on their own. In professional research usually prime focus, Cassegrain focus and coudé focus are being used. Reflector telescopes are very commonly used in science and by 2001 there were no less than 49 reflector telescopes with primary mirrors having diameters of 2 meters or even more.