Vegan
Vegans were a species only mentioned in the shooting script for The Motion Picture (dated ). The script briefly mentioned "high-domed Vegans" as an example of the aliens present in the Starfleet Headquarters scenes.  

Steven Lance's character was described as "an alien being from the planet Vega" in a publicity photo.  However, he was later identified as a Rhaandarite.

See also
Vegan choriomeningitis
Vegan D virus
Vegan system

it:Vegano
Unused production material