Blonde Girl By The Mirror

Cold mirrors are dielectric mirrors that reflect the entire visible light spectrum, while efficiently transmitting infrared wavelengths. These are the converse of hot mirrors.
Corner reflectors use three flat mirrors to reflect light back towards its source. They are used for emergency location, and even laser ranging to the Moon.
Hot mirrors reflect infrared light while allowing visible light to pass. These can be used to separate useful light from unneeded infrared to reduce heating of components in an optical device. They can also be used as dichroic beamsplitters. (Hot mirrors are the converse of cold mirrors.)
Metallic reflectors are used to reflect infrared light (such as in space heaters), or microwaves).