Sir William Heaton Horrocks KCMG, CB (25 August 1859 – 26 January 1941) was an officer of the British Army remembered chiefly for confirming Sir David Bruce's theory that Malta fever was spread through goat's milk. He also contributed to the making safe of water, developing a simple method of testing and purifying water in the field. Because of his work, he became the first Director of Hygiene at the War Office in 1919.