Elizabeth Mainway is the owner of health care company, Declodyne, that owns Radley Sanitarium. (Until Season 6, where Radley Sanitarium is under new ownership)
She's not easy to approach due to her high position. Her company generates millions of dollars.
She first appears in this episode when she is approached by Spencer and Toby, who ask her to release a statement stating that Marion Cavanaugh's death was not a suicide. After Spencer threatens to lead a smear campaign online about Declodyne, Mainway reluctantly agrees to issue a statement.