Agatha Sadler and Bradford "Brad" Sadler are two of Jerry and Terri Sadler's distant relatives in Ghost Beach.
History
Agatha and her husband Bradford Sadler let Jerry and Terri visit them. Late one night, Agatha asks the kids to go to the nearby beach and look for her beach towel, but Jerry and Terri instead go to the caves.
Near the end of the novel, Harrison Sadler's dog barks at Agatha and Bradford. Agatha responds by saying, "Bad Dog, now you've discovered our secret, what a pity, so what do we do with these two kids Brad?" Revealing her and her husband to be ghosts as well.