Ambassador Kollos was a noncorporeal Medusan renowned for his aptitude in spatial navigation and rendered a virtual recluse by his unfortunate visage, which shocks humans into insanity on sight.
Travelling within his own transport chamber for safety during his transport to the Federation, Ambassador Kollos checked aboard the USS Enterprise with the human engineer, Larry Marvick, and telepath, Miranda Jones. Miranda had no fear of injury because she was blind, though she did not advertise that fact. Marvick was smitten with Jones, but when spurned he approached Kollos in a jealous rage, sending the starship out of the galaxy in his resulting madness.
Commander Spock successfully mind melded with Kollos so that he could navigate the ship back and bypass the effects of the galactic barrier's sensory effects on humanoids thanks to Kollos' navigation abilities. He forgot to wear a protective visor when breaking the meld, and Captain Kirk realized too late to save him. Only Jones could restore his sanity. (TOS: "Is There in Truth No Beauty?")