Who is Henrietta from Sybil and what is their importance?

Henrietta (Hattie) is Sybil's mother. She is a staunch woman, who was largely neglected as a child, and married for convenience..... not for love. Hattie also suffered from schizophrenia, which was diagnosed at the Mayo Clinic. Hattie never wanted children and during Sybil's early life, she was cared for by her father and grandmother.

Hattie's motherly instinct never takes over, but she does take over her daughter's care. As a mother, she is an abusive creature without conscience. She even goes so far as to neglect to call Sybil's doctor in an emergency.