Many living systems native to the Arctic and Antarctic regions express antifreeze proteins (AFPs) or antifreeze glycoproteins (AFGPs) that recognize and bind to specific faces of ice crystals, thereby inhibiting ice growth. The non-colligative freezing point depression induced by these proteins results primarily from their unique chemical structures. This review describes the various classes of AF(G)Ps, their structural hierarchy, their mechanisms of action, and novel synthetic antifreeze compounds. The mechanism of action of AF(G)Ps displays a high degree of precision present in natural systems. The varied chemical structures of AFPs with similar antifreeze activities suggest convergent evolution. Structural studies of AFPs from insects, plants and bacteria have revealed unusual beta helical structures. A variety of AF(G)P analogs have been synthesized and have revealed the mechanisms underlying the action of AF(G)Ps. The utility of AF(G)Ps and their analogs in cryopreservation, cryosurgery, and the food industry motivates the development of new artificial antifreeze agents.