Nepenthes tenax ( /nɨˈpɛnθiːz ˈtɛnæks/; from Latin: tenax "tenacious") is a lowland species of tropical pitcher plant native to northern Queensland, Australia. It is the third Nepenthes species recorded from the continent and its second endemic species. Nepenthes tenax is closely related to the two other Australian Nepenthes species: N. mirabilis and N. rowanae.
Nepenthes tenax grows to a height of around 100 cm with pitchers rarely exceeding 15 cm. The stem is usually self-supporting. In its natural habitat, it is sympatric with N. mirabilis and N. rowanae. Simple and complex natural hybrids involving both of these species have been found.