Charles William Mills, 2nd Baron Hillingdon (26 January 1855 – 6 April 1919) was a British banker and Conservative politician who sat in the House of Commons from 1885 to 1892.
Mills was the son of Charles Mills, 1st Baron Hillingdon, and his wife Lady Louisa Isabella, daughter of Henry Lascelles, 3rd Earl of Harewood. He was a lieutenant in the Queen's Own West Kent Yeomanry and a partner in the banking firm of Glyn, Mills & Co.
In the 1885 general election, Mills was elected as Member of Parliament (MP) for Sevenoaks, and held the seat until he stood down from the Commons at the 1892 general election. In 1898 Charles Mills inherited the title Baron Hillingdon.
In the same year Hillingdon commissioned Edwin Lutyens, who was then working locally, to design Overstrand Hall. Work began on Overstrand Hall in 1899 and it was completed by 1901. Nikolaus Pevsner considered it one of Lutyens' most remarkable buildings, but other critics of the day thought it "lacked the picturesqueness of his best works".
Mills was godfather to Harry Elkins Widener , son of George Dunton Widener who both perished on the Titanic
Hillingdon died in April 1919, aged 64, and was succeeded in the barony by his son Arthur.