Princess Charlotte is not to be confused with Charlotte Casiraghi, her great-granddaughter.
Born Charlotte Louise Juliet Louvet on 30 September 1898, Princess Charlotte was the daughter of HRH Prince Louis II of Monaco and Marie Juliette Louvet (a laundrywoman's daughter). Although there is debate as to whether or not Louis married Marie, Louis's father Prince Albert did not approve of a marriage, and Charlotte was declared illegitimate.
Charlotte was eventually declared to be the legitimate daughter of Louis and the heir to the throne through laws passed in 1911 and 1918, to provide for a Monégasque heir; the throne would have gone to the Duke of Urach.
In 1919, Charlotte married Count Pierre of Polignac, who in accordance with Monégasque law took the Grimaldi surname and became a Prince of Monaco. The couple had two children, Antoinette Louise Alberte Suzanne and Rainier Louis Henri Maxence Bertrand before their divorce in 1933.
On 30 May 1944, Charlotte ceded the rights to the throne of Monaco to Rainier on the condition that he outlived her. After Ranier rose to the throne, she moved to Marchais (the Grimaldi's estate outside Paris). She also went to college, receiving a degree in social work, and turned Marchais into a rehabilitation center for ex-convicts.
Princess Charlotte died on 15 November 1977 in Paris, France.
Credit to: Princess Charlotte of Monaco Wikipedia article, CatherineB's Princess Caroline of Monaco writeup, www.monaco.gouv.mc.