Nepenthes rajah is a carnivorous pitcher plant species of the family Nepenthaceae. It is endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Malaysian Borneo. "Nepenthes rajah" grows exclusively on serpentine substrates, particularly in areas of seeping ground water where the soil is loose and permanently moist. The species has an altitudinal range of a.s.l. and is thus considered a highland or sub-alpine plant. Due to its localised distribution, "N. rajah" is classified as an endangered species by the IUCN and listed on CITES Appendix I.