Unnamed Alpha and Beta Quadrant nebulae
The following is a list of unnamed Alpha and Beta Quadrant nebulae.

Amleth system nebula 
Located in the Alpha Quadrant, this nebula was an emission nebula in the Cardassian Union. It was notable for its size – it encompassed the entire Amleth system. The planet  and the Loval system were located in the same sector as this nebula.

In 2372, Dukat suggested that K'Temang's next Cardassian target could be Amleth Prime. Major Kira Nerys pointed out that the nebula would render his Bird-of-Prey's cloaking device useless. ()

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Andorian hideout nebula 

This nebula was used by Shran and his forces to hide from the Vulcans. ()

Brown nebula in Cardassian space 

This nebula was seen in Cardassian space. An escape pod containg Jake Sisko, Nog, and Dorian Collins flew towards this nebula after the destruction of the Valiant. ()

Brown nebula visited by Discovery 
This distinct reddish brown nebula, resembling clouds and lighted by periodic flashes of light, was visited by  during the period it was under the command of Christopher Pike. The ship cleared it while Pike and Michael Burnham discussed Spock's knowledge of the Red burst phenomenon. ()

Cardassian dark matter nebula 
This dark matter nebula was located in Cardassian space and contained at least one planet.

In 2374, it was located near a ketracel-white facility destroyed by Captain Sisko. The ship Captain Sisko used was destroyed when it was attacked by two additional Jem'Hadar fighters that caused the already ship to crash on the planet within the nebula. Sisko and his crew, along with the Vorta Keevan eventually were rescued. ()

Cardassian blue and red nebula 

This nebula existed near Cardassia Prime. ()

Cardassian blue nebula 

In 2371, Tom Riker took the  into a nebula to hide the ship from Cardassian warships after Kira Nerys sabotaged the cloaking device. ()

Data's dream nebula 
This nebula was seen in a dream by Data in 2369. ()

Epsilon IV nebula 
Captain Ransom once hid from a Klingon Bird-of-Prey for three days in a nebula near Epsilon IV. ()

Enterprise-E nebula 

This nebula located in Federation space was traversed by the  in 2373, shortly before it was assigned to patrol the Romulan Neutral Zone after the Borg sent a cube to Earth. ()

Kovaalan nebula 
This nebula, located in the Delphic Expanse, contained a the terminus of a subspace corridor and was controlled by the Kovaalans. In 2154,  attempted to access the subspace corridor within the nebula to rendezvous with Degra, but was forced to fight with the Kovaalan starships in the nebula. While Enterprise managed to escape, the damage inflicted on its impulse manifold caused it to emerge in 2037 when it came out of the other terminus of the corridor. Enterprise remained in the expanse for the following 117 years, until it encountered the past version of itself. This Enterprise helped its past counterpart reach the corridor without traveling to the early 21st century. Instead, it rendezvous with Degra's ship early, thus negating the alternate version of the past in which it time traveled. ()

Magenta nebula

In 2374, a Dominion fleet gathered near this nebula to counter Operation Return. ()

Red nebula
Some time after Spock fled Starbase 5,  followed Spock's shuttle, by then piloted by  into a red nebula containing hydrogen. ()

Suliban nebula 

This deep red nebula was located near Paraagan II and contained a Suliban helix. 

In 2152, the  captured  and took it to this nebula after the Cabal destroyed mining colony on Paraagan II. After Enterprise faked a warp core breach, the Suliban towed the ship out of the nebula and it escaped. ()

 Unnamed Alpha