Mr. Sock was a Sok'an, and the first officer of the USS Armitage. Captain Clinch was his host, and Mr. Sock seemed to have much influence over him.
History
During the ship's visit to the rebuilt Farpoint Station, the station was attacked by a Star-jelly. Sock advised the captain to retreat, saying that the conflict was none of their business. The captain agreed. (ST comic: "Brief Encounter at Farpoint")
Captain Clinch eventually promoted Sock to First Officer, which seemed strange to the other crewmembers, to whom Mr. Sock appeared to be an ordinary sock puppet. Soon afterward, the Armitage visited the Sok'an homeworld, Sok'drwr, where Sock battled another Sok'an in the ritual of Pai'ring, in which he was to be paired with another Sok'an. Sock was mortally wounded during the battle, but luckily Ensign Bunsen was quickly able to darn him, thus saving his life. However, because of the darning, he could not be paired. (ST comic: "A Sock Time")