Born Diana Spencer, she married Prince Charles in 1981 in a ceremony watched by 750 million people worldwide. Her humanitarian work — particularly her campaigns against landmines and her support for AIDS patients — made her one of the most beloved public figures of the twentieth century before her death in Paris in 1997.

Leibniz independently developed calculus at roughly the same time as Isaac Newton, and his notation — including the integral sign and differential notation — is the version mathematicians still use today. He was also a pioneering logician and philosopher, contributing foundational ideas about logic, metaphysics, and the nature of space and time.

One of the most prolific writers of the nineteenth century, George Sand (born Amantine Lucile Aurore Dupin) wrote over seventy novels and caused scandal by wearing trousers, smoking in public, and conducting high-profile love affairs. Her passionate romanticism and social commentary made her a towering literary figure in France.

Semmelweis discovered that handwashing with chlorinated lime dramatically reduced the incidence of puerperal fever in maternity wards, effectively pioneering antiseptic technique. His findings were largely rejected by the medical establishment during his lifetime, and he died in an asylum — vindicated only after Pasteur and Lister popularized germ theory.

Carl Lewis won nine Olympic gold medals across four Games (1984–1996), matching Jesse Owens's legendary four-gold performance at the 1984 Los Angeles Olympics in a single afternoon. His dominance of the 100 metres and long jump made him widely regarded as the greatest track and field athlete of the twentieth century.