Sir William Anderson, KCB (5 January 1835 at Saint Petersburg – 11 December 1898 at Woolwich Arsenal) was an English engineer who also served as director-general of the Ordnance Factories from 1889 to 1898.

He was the fourth son of John Anderson (26 June 1796 - 22 January 1870), a member of the firm of Matthews, Anderson, & Co., bankers and merchants of Saint Petersburg, by his wife Frances, daughter of Dr. Simpson. He was educated at the Saint Petersburg high commercial school, of which he became head. He carried off the silver medal, and although an English subject received the freedom of the city in consideration of his attainments. When he left Russia in 1849 he was proficient in English, Russian, German, and French.

In 1849, he became a student in the Applied Sciences department at King's College, London, and on leaving became an associate. He next served a pupilage at the works of Sir William Fairbairn in Manchester, where he remained three years. In 1855 he joined the firm of Courtney, Stephens, & Co., of the Blackhall Place Ironworks, Dublin. There he did much general engineering work. He also designed several cranes, and was the first to adopt the braced web in bent cranes. In 1863 he became president of the Institution of Civil Engineers of Ireland.

In 1864 he joined the firm of Easton and Amos of the Grove, Southwark, and went to live at Erith, where the firm had decided to construct new works on a riverside site at Anchor Bay, east of Erith's centre. He became a partner, and eventually head, of the firm which at a later date was styled Easton and Anderson. At Erith he had the chief responsibility in designing and laying out the works. Part of the business of the firm at that time was the construction of pumping machinery. Anderson materially improved the pattern of centrifugal pump devised by John George Appold.

While in Erith, he also contributed to the establishment of local schools, serving for 27 years on the Erith School Board, which he chaired from 1886 until his death. He was also actively involved with local churches.

In 1870 he went to Egypt to erect three sugar mills for the Khedive Ismail, which he had helped to design. In 1872 he presented to the Institution of Civil Engineers an account of the sugar factory at Aba-el-Wakf (Minutes of Proceedings, 1872–3, xxxv. 37–70), for which he received a Watt medal and a Telford premium.

Anderson next turned his attention to gun mountings of the Moncrieff type, and designed several for the British government, which were made at the Erith works. In 1876 he designed twin Moncrieff turret mountings for 40-ton guns for the Russian admiralty, which were made at Erith and proved highly successful. Later he designed similar mountings for 50-ton guns for the same country, and about 1888 he designed the mountings for the battleship HMS Rupert.

About 1878–82 he was occupied with large contracts which his firm had obtained for the waterworks of Antwerp and Seville. To render the waters of the river Nethe, which was little better than a sewer, available for drinking purposes, he invented, in conjunction with Sir Frederick Augustus Abel, a revolving iron purifier, which proved perfectly effectual. He contributed a paper on the Antwerp Waterworks to the Institution of Civil Engineers (Minutes of Proceedings. lxxii. 24–83), for which he received a Telford Medal and premium.