Terkim was an El-Aurian male, Guinan's maternal uncle. He was considered to be the family misfit and a bad influence. Most of his acquaintances had long since stopped spending much time with him.
Terkim had a bond with his niece, Guinan. Despite their family's opinion of him, and the fact that they told her to stay away from him as well, she spent enough time with him to realize that he was the only one in her family, other than herself, who had a sense of humor. Her mother would say she reminded her of Terkim.
Guinan later compared Reginald Barclay to Terkim in 2366 after Geordi La Forge expressed his reservations about the engineer not fitting in. (TNG: "Hollow Pursuits")
This character was only mentioned in dialogue.