Bettencourt's net worth in March was 33 billion euros, Forbes magazine estimated, making her the richest woman in the world and the 14th richest person on the planet .
She was rarely seen in public since leaving the L'Oréal board in 2012 but her name remained in the headlines as members of her entourage were charged with exploiting her failing mental health.
Liliane Bettencourt was born in October 1922, in Paris, where her father Eugène Schueller was marketing a hair dye formula he had invented in 1907.
The product took off and the company soared to world cosmetics dominance with nearly 90,000 employees in 140 countries and sales of 25.84 billion euros in 2016.
Both her father, who had been involved in the right-wing Cagoule coup plot in the 1930s and her husband, André Bettencourt, were accused of being Nazi collaborators during World War II, although the latter became involved with the resistance towards the end of the conflict.
André Bettencourt later served as a government minister under presidents Charles de Gaulle and Georges Pompidou.
Inheriting the L'Oréal fortune from her father in 1957, Liliane Bettencourt chose not to be directly involved in running it, although she made her presence felt on the company board.
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In 2008 her estranged daughter Francoise Bettencourt-Meyers, who is on the L'Oréal board, filed a lawsuit against her mother over funds she had given to celebrity photographer and confidant François-Marie Banier, who was eventually given a four-year suspended prison sentence for abuse of a vulnerable person.
The scandal took on a political turn when two men charged with overseeing her fortune, Patrice de Maistre and Pascal Wilhelm, were accused of abusing their positions.
De Maistre was accused of persuading her to hand over envelopes of cash to Nicolas Sarkozy's 2007 presidential campaign.
The charges against Sarkozy were dropped in October 2013 due to lack of evidence.
She was also accused of tax evasion in a series of media revelations.
Liliane Bettencourt had been declared unfit to run her own affairs in 2011 after a medical report showing she had suffered from "mixed dementia" and "moderately severe" Alzheimer's disease since 2006.
Liliane Bettencourt, a life in dates
21 October 1922: born Liliane Schueller in Paris to L’Oréal founder Eugène Schueller and Louise Madeleine Berthe Doncieux, a pianist;
1927: Death of Louise Madeleine Berthe Doncieux;
8 June 1950: Marries André Bettencourt;
1937: Internship at L’Oréal;
1953: Daughter Françoise Bettencourt Meyers born;
1957: Inherits father’s fortune on his death;
1987: Sets up charitable foundation Fondation Bettencourt Schueller, notably involved in fighting Aids;
2007: Death of André Bettencourt;
2008: Françoise Bettencourt Meyers accuses photographer François-Marie Banier of abuse of a vulnerable person, sparking legal action;
2009: Press reports reveal that she was taxed at 9.0 percent on income including 280 million euros of L’Oréal dividends;
2010: Revokes Banier’s universal legatee status and reconciles with daughter, Eric Woerth, aide to President Nicolas Sarkozy, is accused in the press of improperly profiting from Bettencourt’s fortune for political ends, awarded Légion d’honneur for work of Fondation Bettencourt Schueller;
2011: Placed under supervision because of deteriorating mental faculties, leaves L’Oréal board;
20 September 2017: Dies at home in Neuilly-sur-Seine.