Bennett received star billing on the gothic daytime television soap opera Dark Shadows, which attracted a major cult TV following, for its entire five-year run, 1966 to 1971, receiving an Emmy Award nomination in 1968 for her performance as Elizabeth Collins Stoddard, mistress of the haunted Collinwood Mansion. Her other roles on Dark Shadows were Naomi Collins, Judith Collins Trask, Elizabeth Collins Stoddard PT, Flora Collins, and Flora Collins PT. In 1970, she appeared as Elizabeth in House of Dark Shadows, the feature film adaptation of the series. She declined to appear in the sequel Night of Dark Shadows however, and her character Elizabeth was mentioned as being recently deceased.