Ablative composites are highly endothermic sacrificial thermal protection materials that are indispensable to the aerospace industry. Polymeric ablatives are the most versatile and the largest class of thermal protection materials due to their capability to be to varied hyperthermal environments. Carbon/carbon composites have outstanding mechanical properties at higher temperatures but they are susceptible to oxidation. The oxidation is addressed by matrix modification, application of a coat of ultrahigh temperature ceramics (UHTC), or also by the use of nanostructure-toughened UHTC coatings as discussed in this article. The article presents a comprehensive review of the science and technology of four distinct groups of ablative composites (carbon/carbon, carbon/phenolic, carbon/elastomeric and carbon/ceramic). The selection of the best material formulations for a given environment is ratified by the testing techniques, which have also been reviewed along with a brief discussion on the composites recycling technologies and their environmental and economic impacts.