NX is a starship registry number prefix in use by both the Earth and Federation Starfleets.
In the Earth Starfleet it was used to represent the NX-class starships.
In the Federation Starfleet, they would come to be used by experimental starship designs that generally would become the first starship (or prototype) of their class.
Examples of NX Class Starships
- Enterprise (NX-01)
- ISS Enterprise (NX-01)
- Columbia (NX-02)
- Challenger (NX-03) (ENT novel: The Romulan War: Beneath the Raptor's Wing)
- Discovery (NX-04) (The Romulan War: Beneath the Raptor's Wing)
- Atlantis (NX-05) (The Romulan War: Beneath the Raptor's Wing)
- Endeavour (NX-06) (The Romulan War: Beneath the Raptor's Wing)
- Intrepid (NX-07) (TNG novel: Indistinguishable From Magic)
- ISS Avenger (NX-09)