Star Trek: The Next Generation
Episode: TNG 151 - Survivors, The

An immortal race of pure energy, capable of creating disguises and false surroundings by manipulating matter and energy instantaneously-as does the one who took human form on Earth under the name of Kevin Uxbridge, later discovered in 2366. Uxbridge carried guilt over the instantenous elimination of the 50-billion Husnock race.