Catherine Henriette de Bourbon (11 November 1596 – 20 June 1663) was an illegitimate daughter of King Henry IV of France and his long-term maîtresse en titre Gabrielle d'Estrées. She was declared legitimate on 17 November 1596 at the Abbey of St. Ouen in Rouen and married into the Princely House of Guise.

Born on 11 November 1596 in Rouen, France, she was baptised on 17 November 1596. At her birth, Queen Elizabeth I of England sent a special ambassador who also proposed a new treaty between the two nations. Then, surprising everyone, Spain attacked Amiens. One of the first things Catherine Henriette's mother Gabrielle did was to ask the people of France to contribute financially to the war effort while she herself pawned her jewellery; in doing so she raised a substantial fortune.

In her youth, she was known as Mademoiselle de Vendôme, derived from the Duchy of Vendôme which had been in possession of the House of Bourbon since 1393. Her older brother, César, was legitimised in 1595 and given the title of Duke of Vendôme. César would later scheme against the crown against Cardinal Richelieu in the Fronde with their younger half-brother Gaston. Her youngest full sibling, Alexandre, was born in 1598 and died in 1629.

When she was just three, her 26‑year‑old mother died of an attack of eclampsia after giving birth to a stillborn child. As a result of her mother's death, Catherine Henriette inherited her wealth in her own right. Her mother's duchy, Beaufort, was given to her older brother, César.

In 1610, her father was assassinated outside the Louvre Palace on 19 May. This left her eight-year-old half-brother Louis XIII the new king, with a regency under the power of his mother Marie de' Medici, who hated the royal bastards.

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