Drella

From Memory Alpha, the free Star Trek reference.

The Drella of planet Alpha Carinae V derived nourishment from the emotion of love. The Drella exist without form in conventional sense and is a mass of energy of highly cohesive electromagnetic field and very similar to Mellitus, gas cloud creature of Alpha Majoris I, and Redjac that existed for centuries by journeying from planet to planet, including Earth, Mars, Alpha Eridani II, Rigel IV, Argelius II and Deneb II. (TOS: "Wolf in the Fold")