Hayley Catherine Rose Vivien Mills is an English actress. The daughter of Sir John Mills and Mary Hayley Bell, and younger sister of actress Juliet Mills, Mills began her acting career as a child and was hailed as a promising newcomer, winning the BAFTA Award for Most Promising Newcomer for Tiger Bay, the Academy Juvenile Award for Pollyanna and Golden Globe Award for New Star of the Year – Actress in 1961. During her early career, she appeared in several films for Walt Disney, and is perhaps best known for her dual role as twins Susan and Sharon in the Disney film The Parent Trap.
During the late 1960s she began performing in theatrical plays, and played in more mature roles. The age of contracts with studios soon passed. Although she has not maintained the box office success or the Hollywood A-list she experienced as a child actress, she has continued to make films and TV appearances.
From 2007 to 2012, Mills played Caroline, a main character in the ITV1 Series Wild at Heart.