Sir James David Edgar, KCMG PC QC (August 10, 1841 – July 31, 1899) was a Canadian politician.

Fred Cumberland, a partner in the O&PJR venture, formed a rival company called the Northern and Pacific Junction Railway.

Edgar was undaunted by these setbacks and in 1889 started a new company called the Belt Line Railway in Toronto.

The land developers of these areas required either a commuter railway or a system of bridges to ease access to their properties for buyers.

He used his experience to become the Liberal's railway critic when he returned to Parliament (and the Opposition benches) through an 1884 by-election.

He also argued against the concept of Imperial Federation, for greater Canadian independence from Britain, and in favour of reciprocity with the United States.

When the Liberals formed a government under Wilfrid Laurier following the 1896 federal election, Edgar was nominated to become Speaker of the House of Commons of Canada, and was given a knighthood by Queen Victoria.