Helensburgh is a Scottish town historically part of Dunbartonshire, but since local government reorganisation in 1995 in Argyll and Bute, on the north shore of the Firth of Clyde. It was founded in the eighteenth century in the style of Edinburgh New Town, as a seaside resort.

Helensburgh is the birthplace of Charles Rennie Mackintosh, and he designed Hill House in the town. The town is also notable as a ferry port for boats to Gourock and for the Waverley paddle steamer, and as the birthplace of John Logie Baird.

Its population at the 2001 census was 14,626.

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Helensburgh, New South Wales is also a suburb of Sydney, Australia.