Sydney Bryan Donkin (24 June 1871 – 12 November 1952) was a British civil engineer. His parents were Bryan Donkin Junior and Georgina Dillon. Donkin was educated at University College, London before beginning work for Sulzer Brothers, mechanical engineers, later the Sulzer company. Whilst based at this company's headquarters in Switzerland he became interested in Alpine climbing and spent much of his spare time climbing the nearby peaks. He was a founding member of the Climbers' Club and served on their committee in 1908 and later as vice-president and president.