The Littles (1983)

The series, set in the town of Grand Valley, follows the adventures of Henry Bigg, a human who befriends Tom and Lucy Little, two small human-like creatures who live in the walls of homes. Focus of the series are the efforts of the evil Dr. Hunter and his assistant, Peterson, to discover if what he believes is another life form (which he calls the Littles) really do exist, and the efforts of the Littles to remain a secret.