Anabis

The Anabis is a vast gaseous intelligence that permeates the galaxy known as M33, and feeds on the death of any life form on the planets under its influence. This strange being started life as a simple, odorless, transparent mist which somehow gained life on the surface of a swamp planet. It grew out of proportion, covering its entire world, solar system and finally the galaxy; and started actively harvesting life, converting available worlds around millions of suns into exact copies of its tropical home planet and feeding on the abundant animal and vegetable life which developed there. Although the Anabis does't actively kill, it needs to be present at the moment where its prey dies so that it naturally feeds on their life essence.

Appearances

 * M33 in Andromeda, by A. E. Van Vogt (1943)
 * The Voyage of the Space Beagle, by A. E. Van Vogt (1950)