Non-corporeal lifeform
A non-corporeal lifeform, also called an incorporeal, non-physical lifeform, or formless, was a classification of species that did not maintain a corporeal form, but may or may not be capable of assuming physical form.

Physiology 
The properties of what made a lifeform non-corporeal were loosely defined, as they existed under many forms, such as space-dwelling lifeforms, multispectrum particle lifeforms, electromagnetic lifeforms, and included interphasic species. ()

In describing Trelane, Spock suggested describing him under several classifications, including "pure mentality", "force of intellect", "embodied energy", or "superbeing". ()

The planet Meridian and its inhabitants existed in a non-corporeal state for sixty year intervals. ()

Often they were composed of various forms of coherent gas or energy. () Of the latter, these were sometimes known by the term energy being, energy force, or energy form, and included trianic-based energy beings. (; ) 

The Zetarians existed as the life force of their former corporeal existence, and were a collective composed of "the desires, the hopes, the mind and the will of the last hundred of Zetar." Together they sought out another corporeal host "through whom [they could] see and speak and hear and live out our lives." ()

Many had the ability to pass through solid matter or had no mass. These non-corporeals also possessed the minds of corporeal beings. (; ) During the 's mission, the crew encountered a species referred to as "Wisps". They had the ability to possess the minds of humanoids, one notable exception being Doctor Phlox. () Likewise, the Organians possessed the same abilities, without exception. () The Komar of the Delta Quadrant also possessed the same abilities. ()

Generally, non-corporeal species did not utilize technology, compensating with intrinsic physiological capabilities. One exception was in the case of the child-being Trelane who possessed a mirror machine capable of performing matter-energy conversion. () Those that possessed the intrinsic capacity to travel at warp speed, included the Companion, the dikironium cloud creature, and the Zetarians. () When coalesced, Q's forcefield-grid had the capabilities of traveling at warp 9.9. ()

More advanced non-corporeal races, such as the , had evolved beyond the need for sustenance, and wielded substantial control over space and time, or possessed all around omnipotence. () 

Others required sustenance to survive. Some non-corporeal entities absorbed and utilized energy directly from their environment. (; ) Others, such as Redjac or the Beta XII-A entity, derived sustenance from the emotions of humanoid lifeforms. () The dikironium cloud creature of Tycho IV forcibly extracted the corpuscles of iron-based blood and fed on that. ()

In early 2374, Kes became a non-corporeal lifeform after the 's encounter with Species 8472 in the Delta Quadrant, and the growth of her telekinetic abilities. ()

See also
List of non-corporeal species 
 List of unnamed non-corporeal species
List of powerful and godlike beings
Lifeform classifications