The gormagander (xenologic classification: Federation species 283732) was a sentient cosmozoan, or non-atmospheric organism, that lived in the vacuum of space. It was described as a "space whale", though it was not technically a marine animal.
Beckett Mariner also referred to the race that sent the Whale Probe to Earth in 2286 as "space whales." (LD: "Second Contact"; DIS: "Magic to Make the Sanest Man Go Mad", "That Hope Is You, Part 2")
Although this species was a target for hunting, their numbers dwindled due to other reasons. Gormaganders spent their lives feeding off alpha particles in solar winds. Often they were so consumed by this task that they ignored all other instincts, including reproduction. As of 3189, they held the distinction of the species with the longest tenure on the Federation's Endangered Species List. (DIS: "That Hope Is You, Part 2")
Run-ins with this species were considered extremely rare, with only fifty-seven near-miss encounters by starships recorded between 2246 and 2256. In late 2256, the USS Discovery came across a female gormagander which appeared to be injured. In an effort to aid the creature and transport it to a xenologic facility, as was required by the Endangered Species Act, the crew unknowingly transported aboard a saboteur, Harcourt Fenton Mudd, who was hiding inside the creature and who planned on taking the ship for himself. (DIS: "Magic to Make the Sanest Man Go Mad")
Some species consumed the meat of gormaganders. Skewers of gormagander meat were available at the Orion embassy outpost on Qo'noS. In 2257, Sylvia Tilly ate some and enjoyed the taste, though she spat it out upon being told what it was. (DIS: "Will You Take My Hand?")
"Penetrating a space whale" was a crime in the Federation, and was among the accusations against Harcourt Fenton Mudd while he was "Wanted" in the late 2250s. Tevrin Krit was disgusted to read the accusation, to which Mudd noted without clarifying: "You kind of had to be there." (ST: "The Escape Artist")
In 2399, Doctor Agnes Jurati told Captain Cristóbal Rios and Raffi Musiker that she wanted to be "the fun crew member who says, 'Let's hide in that comet', and it turns out to be a giant gormagander or something." (PIC: "Nepenthe")
In 3052, the Federation recorded a scan of a young gormagander pup that was of particular interest. This hologram was later displayed in Su'Kal's world on the KSF Khi'eth. (DIS: "That Hope Is You, Part 2")