The last decade of her life was dogged by illness, probably caused by the brain tumor that was to kill her at the age of 53.

A year later, Mary Shelley returned to England and from then on devoted herself to the upbringing of her son and a career as a professional author. In 1822, her husband drowned when his sailing boat sank during a storm near Viareggio. The Shelleys left Britain in 1818 for Italy, where their second and third children died before Mary Shelley gave birth to her last and only surviving child, Percy Florence Shelley. In 1816, the couple famously spent a summer with Lord Byron, John William Polidori, and Claire Clairmont near Geneva, Switzerland, where Mary conceived the idea for her novel 'Frankenstein'. They married in late 1816, after the suicide of Percy Shelley's first wife, Harriet. Over the next two years, she and Percy faced ostracism, constant debt, and the death of their prematurely born daughter. Upon their return to England, Mary was pregnant with Percy's child. Together with Mary's stepsister Claire Clairmont, Mary and Shelley left for France and traveled through Europe. In 1814, Mary began a romance with one of her father's political followers, the then married Percy Bysshe Shelley. When Mary was four, her father married a neighbor, with whom, as her stepmother, Mary came to have a troubled relationship. After Wollstonecraft's death less than a month after her daughter Mary was born, Mary was raised by Godwin, who was able to provide his daughter with a rich, if informal, education, encouraging her to adhere to his own liberal political theories.

Her father was the political philosopher William Godwin, and her mother was the philosopher and feminist Mary Wollstonecraft.

She also edited and promoted the works of her husband, the Romantic poet and philosopher Percy Bysshe Shelley. Mary Wollstonecraft Shelley (née Godwin 30 August 1797 - 1 February 1851) was an English novelist, short story writer, dramatist, essayist, biographer, and travel writer, best known for her Gothic novel 'Frankenstein: or, The Modern Prometheus' (1818).

Mary shelley mary wollstonecraft