Hanar

Hanar was a member of agents from the Kelvan Empire lead by Rojan. Their purpose was to find planets that the empire would invade and colonize. Their ship was destroyed and they hijacekd the Enterprise to take them home. While in Human form he and his fellow agents discovered human weakness and emotions which distracted them and enable Spock and Kirk to retake the ship. Doctor McCoy tried to make Hanar nervous and angry by "treating" him with uncountable useless medicine and medical examination. (TOS: "By Any Other Name")

Hanar was played by actor Stewart Moss.