Jane Lampton Clemens, usually known as Jean Clemens, (July 26, 1880–December 24, 1909) was the youngest of the three daughters of Samuel Langhorne Clemens, better known by his pen name Mark Twain, and his wife Olivia Langdon Clemens. She was born in Hartford, Connecticut. She died near Redding, Connecticut by drowning in a bathtub following a heart attack thought to be related to her epilepsy, at her father's home in Stormfield.
According to Mark Twain's Autobiography, Jean Clemens, like her mother, was a kind-hearted person and particularly fond of animals. She founded or worked with a number of societies for the protection of animals in the various locations where she lived.
She had epilepsy from age fifteen, which her father attributed to a head injury she had suffered at age eight or nine. The family spent years seeking cures in the United States and Europe. Twain also attributed her mood swings and sometimes erratic behavior to her uncontrolled epilepsy.