Kollos

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.

Traveling within his own transport chamber for safety during his transport to the Federation, Ambassador Kollos checked aboard the USS Enterprise (NCC-1701) with a Human engineer, Larry Marvick, and a Human telepath, Miranda Jones. Jones was unaffected by Kollos' appearance because she was blind, though she did not advertise this fact. Marvick was smitten with Jones, but when spurned he approached Kollos in a jealous rage, sending the starship out of the Milky Way Galaxy in his resulting madness.

Commander Spock successfully joined with Kollos (perhaps with a mind meld) so that he could navigate the ship back and bypass the galactic barrier's sensory effects on humanoids, thanks to Kollos' navigational abilities. The joined Spock forgot to wear a protective visor when breaking the link, and Captain Kirk realized too late to save him. However, Jones joined with Kollos and restored the Vulcan's sanity. 

Kollos