Jean-Baptiste Alphonse Karr (24 November 1808 – 29 September 1890) was a French critic, journalist, and novelist.
Karr was born in Paris to German pianist and composer Henri Karr (1784–1842), and after being educated at the Collège Bourbon, became a teacher there. Some of his novels, including his first, Sous les Tilleuls (1832), were autobiographical romances. A second novel, Une heure trop tard, followed next year, and was succeeded by many other popular works. His Vendredi soir (1835) and Le Chemin le plus court (1836) continued the vein of autobiographical romance with which he had made his first success. Geneviève (1838) is one of his best stories, and his Voyage autour de Mon Jardin (1845) was deservedly popular. Others were Feu Bressier (1848), and Fort en thème (1853), which had some influence in stimulating educational reform.
In 1855 he went to live in Nice, where he indulged his predilections for floriculture, and gave his name to more than one new variety, notably the dahlia (New International Encyclopedia). Indeed, he practically founded the trade in cut flowers on the French Riviera. He was also devoted to fishing, and in Les Soirées de Sainte-Adresse (1853) and Au bord de la mer (1860) he made use of his experiences. His reminiscences, Livre de bord, were published in 1879–1880. He died at Saint-Raphaël (Var).
Karr's brother Eugène was a talented engineer, and his niece Carme Karr was a writer, journalist and suffragist in La Roche-Mabile.
In April 1832, Karr had a shortlived relationship with actress Juliette Drouet. He allegedly borrowed all of her money and never paid it back. Karr was married to Louise Estelle Clémentine (née Renard de Mentule, born 9 December 1815). They first met in late 1833, and married on 10 February 1834. Their first and only child, Thérèse, was born on 2 September 1834. By 1845, the couple had been separated for eight and a half years.