A vacuumbreather was a being that could exist in a vacuum without the assistance of a protective suit or life support. They would survive by consuming materials such as space dust and mineral matter or even pure energy. Such organisms were usually non sentient but there were the occasional sentient beings.
Most notably were the Verpine[source?] as well as the Oswaft, Mynocks, Space slugs, Starweird and Duinuogwuin. Givin might not be considered true vacuumbreathers, but could survive for a day in vacuum conditions due to the peculiarity of their planet. The skin of a Kel Dor allowed them to be in a vacuum for a short time (albeit, only with their breathing masks on.) Kadri'Ra could also survive the vacuum of space for a few days.
- The New Essential Guide to Alien Species (First mentioned)