Daniel Kinnear Clark (17 July 1822 – 22 January 1896) was a Scottish consulting railway engineer.

[7] At his appointment, the GNoSR had made it a condition that Clark should live in Aberdeen, to be close to his duties; but he felt that living in northern Scotland 'would be inimical to his advancement in his profession', preferring to work through an assistant based at Kittybrewster.

[9] Clark returned to consultancy, and patented a device for preventing smoke from being emitted when coal was burned in locomotive fireboxes.

[10] It was used on all GNoSR locomotives built during the terms of office of Clark's successors Ruthven (1855–1857) and William Cowan (1857–1883),[12][11] and was still being fitted to new engines as late as 1890 by Cowan's successor James Manson, although in modified form.

[13][14] Clark wrote several books including the two-volume Railway Machinery, which was considered an authoritative text when it was published in 1855.