Michelangelo Castelli (4 December 1808 - 20 August 1875) was an Italian politician and writer.

Born in Racconigi into a wealthy family of Jacobin ideas, Castelli studied law at the University of Turin, graduating in July 1835.

From 1847 collaborated with the Turin-based newspaper Il Risorgimento, working in the political section alongside Camillo Benso, Count of Cavour, the director of the newspaper.

[1] Friend and confidant of Cavour, Castelli was elected for the first time Member of Parliament of the Kingdom of Sardinia in its first legislature, in 1848.

Deputy for five legislatures (1849-1859) in 1852 he was appointed Secretary of the Ministry of Interior, a position he held until March 1854.