Sir John William Dawson CMG FRS FRSE FGS FRSC (1820–1899) was a Canadian geologist and university administrator.

Of Scottish descent, Dawson attended the University of Edinburgh to complete his education, and graduated in 1842, having gained a knowledge of geology and natural history from Robert Jameson.

One of the many schools built to his design, the Mount Hanley Schoolhouse still survives today, including the "Dawson Desks" named after him.

He entered zealously into the geology of Canada, making a special study of the fossil forests of the coal-measures of Joggins, Nova Scotia, now a UNESCO World Heritage Site.

During the course of his second exploration of the cliffs with Charles Lyell in 1852, he discovered the remains of a tetrapod named Dendrerpeton entombed within a fossil tree.

Over the years, he continued his exploration of the fossil trees, eventually unearthing the oldest known reptile in the history of life, which he named Hylonomus lyelli in honour of his mentor.

[3] From 1855 to 1893 he was professor of geology and principal of McGill University in Montreal, an institution which under his influence attained a high reputation.

[7][2] Sir William Dawson's name is especially associated with Eozoon canadense, which in 1865 he described as an organism having the structure of a foraminifer.

In 1882, while looking to fill the vacancy left at McGill by the death of botanist James Barnston, Dawson contacted Asa Gray of Harvard University for recommendations.