Duncan McLean Marshall (September 24, 1872 – January 16, 1946) was a Canadian journalist, publisher, rancher and politician in the provinces of Ontario and Alberta.

Early success led to the creation of weekly newspaper under the banner The Patron of Industry in January 1896 but it was closed in November of the same year.

During the period Marshall attempted to turn to organization into a political party in the province but did not succeed and he returned to Ontario.

The Conservative leaning Calgary Herald wrote a scathing article on his political history during the run-up to the election, describing Marshall as a carpet-bagger.

Marshall was appointed to cabinet by Premier Alexander Cameron Rutherford to serve as the new Minister of Agriculture and Provincial Secretary November 1, 1909, following the resignation of William Finlay due to his poor health.

[4] Shortly after the 1909 election, Rutherford's government came under intense scrutiny when they were accused of giving loan guarantees to private interests for the construction of the Alberta and Great Waterways (A&GW) Railway that substantially exceeded the cost of construction, and which paid interest considerably above the market rate.

The Alberta and Great Waterways Railway scandal reached the tipping point when Attorney General Charles Wilson Cross suddenly resigned from cabinet on March 9, 1910.

In the next day there were unsubstantiated rumors that Marshall and Minister without Portfolio Prosper-Edmond Lessard had also resigned, though these proved false.

[7][8] Marshall would be re-appointed Minister of Agriculture under the new government of Arthur Lewis Sifton on June 1, 1910, but his provincial secretary position would be given to Archibald J. McLean.

Marshall lost his seat to United Farmers candidate Nelson S. Smith, who received 60.5 per cent of the vote.