This long faced alien was a visitor of the Shipyard Bar at the same time Kirk tried to flirt with Uhura. He sat between the two at the bar and had a drink. He later witnessed the bar fight between Kirk and four Starfleet Academycadets. (Star Trek)
This alien was played by stuntman and creature actor Douglas Tait. Derek Mears was originally cast in the role, but backed out due to scheduling conflicts and recommended Tait as his replacement.
During the production he was called "Brian" by the production team and make-up artists to distinguish him from the other aliens.