George Holt Henshaw (September 1, 1831 – January 10, 1891) was a Canadian engineer and draftsman, who worked as engineer in waterworks and for railway company's in Canada, the United States and Denmark. He is particularly known for drafting the first organizational chart designed by Daniel McCallum.
George Holt Henshaw was born in Montreal, September 1, 1831. At a very early age he demonstrated a strong desire to acquire knowledge of mathematics and drawing. As pupil of the Rector of the Montreal High School, the Reverend G. F. Simpson, who was a University of Cambridge mathematician, he attracted much attention, and while pursuing his studies at the school was advised by the Rector to engage the services of Andrews, professor of Mathematics at Cambridge, who had recently come to Canada to settle. Under the tuition of Andrews he made such rapid progress that he was invited by Alfred Barrett, chief engineer of the Board of Works of Canada, to enter the Government service. His first work was on the improvements and enlargement of the locks of the Lachine Canal in 1847.
In 1849, Henshaw was offered the post of assistant engineer on the construction of the James River and Kanawha Canal, Virginia, and in charge of the divisional drawing offices. From 1852 to 1854 inclusive, he was engaged on the Chicago Water Works and various Railway Surveys in Illinois and Michigan. From 1854 to 1856 on the New York and Erie Railway, and from 1857 to 1859 was resident Engineer on the Trois Pistoles section of the Grand Trunk Railway.
Tn 1860, he was appointed by Tho. Brasse, as Engineer in charge of the Western Division of the Danish Railways. After seven years service in Denmark he returned to Montreal, and from 1869 to 1872 was resident engineer on sections 4 and 11 of the Intercolonial railway. During 1872-73 he was engineer in charge of survey between Three Rivers and Montreal on North Shore railway.