Lord John Cavendish PC (22 October 1732 – 18 December 1796) was a British nobleman and politician.

He was a supporter of Lord Rockingham, and subsequently of the Fox-North Coalition that brought the Duke of Portland to power.

Cavendish lived at Billing Hall, Northamptonshire which he commissioned John Carr to substantially remodel in the fashionable Palladian style around 1776.

A mind totally free from every Vice, and fill'd with Virtues of all kinds, and in each kind of no common rank or form; benevolent, friendly, generous, disinterested, unambitious almost to a fault; Tho' cold in his exterior, he was inwardly quick and full of feeling, and tho' reserv'd from modesty, from dignity, from family temperament and not from design, he was an entire stranger to every thing false and counterfeit: so great an Enemy to all dissimulation active or passive, and indeed even to a fair and just ostentation, that some of his Virtues, obscur'd by his other Virtues, wanted something of that burnish and lustre which those who know how to assay the solidity and fineness of the metal wish'd them to have.

His near alliance to the Duke of Devonshire; his very name, connected with the Revolution of 1688, which secured the liberties of Great Britain; his unblemished reputation, and his talents, though very moderate;—all these qualities combined to impress with esteem, even those who differed most from him in political opinion.