A non-physical entity is an entity that lacks a physical/material body or characteristics. Non-physical entities may be considered hypothetical, e.g. deities of religions no longer conventionally believed in, and used as an example of an imaginary being in analytic philosophy, or they may refer to concepts whose existence is considered in philosophical argument, such as qualia. In esotericism and religions they may refer to gods, spirits, and so on, which either lack a body, or possess a subtle body only, and are generally considered belonging to a supra-physical plane of existence. In philosophy of mathematics, many people consider numbers, spaces, sets, and so forth to be existent and yet not physical.

In philosophy, propositions, meanings, statements, etc, can be defined as non-physical entities.

In the substance dualism branch of philosophy, persons are considered non-physical entities attached to physical bodies.

In the philosophy of mathematics certain existent yet not physical conceptions can be considered non-physical entities, for example numbers, functions, and sets. These are nomally referred to as abstract objects.

Lester William Polsfuss (June 9, 1915 – August 13, 2009)—known as Les Paul—was an American jazz and country guitarist, songwriter and inventor. He was the inventor of the solid-body electric guitar which made the sound of rock and roll possible. He is credited with many recording innovations. Although he was not the first to use the technique, his early experiments with overdubbing (also known as sound on sound),delay effects such as tape delay, phasing effects and multitrack recording were among the first to attract widespread attention.

His innovative talents extended into his playing style, including licks, trills, chording sequences, fretting techniques and timing, which set him apart from his contemporaries and inspired many guitarists of the present day. He recorded with his wife Mary Ford in the 1950s, and they sold millions of records.

Among his many honors, Paul is one of a handful of artists with a permanent, stand-alone exhibit in the Rock and Roll Hall of Fame. He is prominently named by the music museum on its website as an "architect" and a "key inductee" along with Sam Phillips and Alan Freed.