Marella Agnelli (, born Donna Marella Caracciolo di Castagneto (); 4 May 1927 – 23 February 2019) was an Italian noblewoman, art collector and socialite. She was the widow Fiat chairman Gianni Agnelli. She often appeared in the fashion magazine "Vogue." She was named to the International Best Dressed List Hall of Fame in 1963.