La Cousine Bette (French pronunciation: [la kuzin bɛt], Cousin Bette) is an 1846 novel by French author Honoré de Balzac. Set in mid-19th century Paris, it tells the story of an unmarried middle-aged woman who plots the destruction of her extended family. Bette works with Valérie Marneffe, an unhappily married young lady, to seduce and torment a series of men. One of these is Baron Hector Hulot, husband to Bette's cousin Adeline. He sacrifices his family's fortune and good name to please Valérie, who leaves him for a tradesman named Crevel. The book is part of the Scènes de la vie parisienne section of Balzac's novel sequence La Comédie humaine ("The Human Comedy").
The novel's characters represent polarities of contrasting morality. The vengeful Bette and disingenuous Valérie stand on one side, with the merciful Adeline and her patient daughter Hortense on the other. The patriarch of the Hulot family, meanwhile, is consumed by his own sexual desire. Hortense's husband, the Polish exile Wenceslas Steinbock, represents artistic genius, though he succumbs to uncertainty and lack of motivation. Balzac based the character of Bette in part on his mother and the poet Marceline Desbordes-Valmore. At least one scene involving Baron Hulot was likely based on an event in the life of Balzac's friend, the novelist Victor Hugo.