Nārāyaṇa Upanishad is the name of two upanishads.
The tenth chapter of the Taittiriya Aranyaka is also known as the Narayana Upanishad of theYajurveda. It exists in two recensions, now known as the Dravida, of 64 anuvakas, and the Andhra, of 80 anuvakas.
There is a Mahanarayana Upanishad associated with the Atharvaveda, with similar content, in 25 khandas. This also called Tripadvibhuti, listed in the Muktika canon.