Anne Isabella, Lady Ritchie (née Thackeray; 9 June 1837 – 26 February 1919), eldest daughter of William Makepeace Thackeray, was an English writer, whose several novels were appreciated in their time and made her a central figure on the late Victorian literary scene.

She is noted especially as the custodian of her father's literary legacy, and for short fiction that places fairy tale narratives in a Victorian milieu.

She had two younger sisters: Jane, born in 1839, who died at eight months, and Harriet Marian (nicknamed "Minny") (1840–1875), who married Leslie Stephen in 1869.

She was a step-aunt of Virginia Woolf, who penned an obituary of her in the Times Literary Supplement.

Several other works followed: In other writings, she made unusual use of old folk stories to depict modern situations and occurrences, such as Sleeping Beauty, Cinderella and Little Red Riding Hood.