Sir Sidney Montagu (died 25 February 1644) was an English politician who sat in the House of Commons at various times between 1593 and 1642.

He was the grandson of another judge Sir Edward Montagu and his third wife Helen or Eleanor Roper.

[2] Since he was reputed to be a man of great wealth, the Commons at the outset of the Civil War were infuriated by his refusal of their request to contribute £2000 to their cause.

The marriage was very happy: in his will he praised her as a "religious, virtuous woman, as loving and contenting to me as my heart can desire", and left her generously provided for.

Samuel Pepys, as he admitted, owed his start in life to the "chance without merit" which made his great-aunt Paulina the mother of the first Earl of Sandwich.