Castello or Castelló is a surname. Notable people with the surname include:
Abraham Isaac Castello (1726–1789), Italian rabbi, preacher and poet, father of Joseph Castello
Bernardo Castello (1557–1629), Italian Mannerist painter
Castellino Castello (1580–1649), Italian Baroque painter
Dan Castello (1836–1909), American showman, animal trainer, clown and circus director
Dario Castello (1602–c. 1631), Italian composer and violinist
Eduardo Castelló (1940–2020), Spanish racing cyclist
Fabrizio Castello (1562–1617), Italian painter of Genoese origin in Spain, son of Givanni Battista Castello
Félix Castello (1595–1651), Spanish Baroque painter
Florencio Castelló (1905–1986), Spanish actor in Mexican films
Francesc de Paula Castelló Aleu (1914–1936), Spanish Roman Catholic beatified martyr
Giovanni Battista Castello (c. 1500–c. 1579), Italian painter
Ignazio Paternò Castello, Prince of Biscari (1722–1786), Italian polymath, antiquarian, patron of the arts and Sicilian noble
John Castello (1802–1877), Guyanese child actor and newspaper publisher and editor
Joseph Castello (c. 1746–?), Italian Jewish physician
Julia Castelló (born 1990), Spanish Paralympic swimmer
Marco Castello (born 1993), Italian singer-songwriter, composer, record producer and multi-instrumentalist
Marie Castello (1915–2008), American fortune teller and psychic reader
Núria Castelló (born 1971), Spanish backstroke swimmer
Pere Martí Castelló (born 1982), Spanish former footballer
Sandra Castelló (born 1993), Spanish footballer
Sebastian Castello (soccer) (born 2003), Canadian soccer player
Sebastian Castellio (1515–1563), also spelled Castello, French theologian
Valerio Castello (1624–1659), Italian Baroque painter
Vicente Castelló (c. 1585–1636), Spanish Baroque painter
Willy Castello (1910–1953), Dutch-American film actor