William Dawson LeSueur (February 19, 1840 – September 23, 1917) was a Canadian civil servant and author.

He continued to work as a clerk for the post office eventually becoming chief secretary in 1888.

A writer, LeSueur published over 80 articles on a wide variety of topics.

LeSueur was asked by Messrs. Morang and Co. to write a biography of William Lyon Mackenzie for their "Makers of Canada Series".

He was awarded an honorary Doctor of Laws degree from Queen's College in 1900.