Thomas Bertram Costain (May 8, 1885 – October 8, 1965) was a Canadian-American journalist who became a best-selling author of historical novels at the age of 57.

[2] Before graduating from high school, he had written four novels, one of which was a 70,000 word romance about Maurice of Nassau, Prince of Orange.

[citation needed] His first writing success came in 1902 when the Brantford Courier accepted a mystery story from him, and he became a reporter there (for five dollars a week).

His success there brought him to the attention of The Saturday Evening Post in New York City where he was fiction editor for fourteen years.

[citation needed] Raised as a Baptist, he was reported in the 1953 Current Biography to be an attendant of the Protestant Episcopal Church.

He was described as a handsome, tall, broad-shouldered man with a pink and white complexion, clear blue eyes, and a slight Canadian accent.

Costain noted in his foreword that he initially intended the book to be about Bayan and Edward I, but became caught up in the legend of Thomas Becket's parents: an English knight married to an Eastern girl.

His research led him to believe that Richard III was a great monarch tarred by conspiracies, after his death, with the murder of the princes in the tower.