Sir William Christopher Macdonald (10 February 1831 – 9 June 1917) was a Canadian tobacco manufacturer and major education philanthropist in Canada.

Born William Christopher McDonald in 1831 at Tracadie, in what was then the British Colony of Prince Edward Island, he was sixth of seven children of The Hon.

Known today as the Glenaladale Settlers, in Canada the family name had been recorded as McDonald, which he maintained until 1898, when he began using the historical Scottish spelling but without capitalizing the "d".

Although he had limited education, Macdonald quickly showed an entrepreneurial spirit and, joined by his brother Augustine, he organized himself as a broker to handle the shipping of American-made goods to merchants in his native Prince Edward Island.

However, after a ship carrying some of his merchandise sank in an ocean storm, the venture had severe problems and Macdonald closed the business and left Boston.

During this period, Macdonald bought out his brother's stock position and soon began using the great wealth he had earned to undertake philanthropic endeavors.

As a result of these expanded facilities, the university began to establish an international reputation that would attract the likes of Ernest Rutherford to teach and where he did the work which earned him the 1908 Nobel Prize in Chemistry.

However, to ensure McGill was not subjected to other unwanted commercial development that would limit the university's future growth, he purchased and donated 25 acres (100,000 m2) north of the main campus which became the site for Molson Stadium, the gymnasium, and Douglas Hall.

Macdonald's love of nature and rural life led to his establishing a new type of specialized school in cooperation with Dr. James W. Robertson, the then Commissioner of Agriculture and Dairying for the Government of Canada.

Built in Quebec, the Maritime Provinces and Ontario, and aimed at those wanting to make their living in rural agriculture environments, these school's curriculum included manual training programmes, domestic sciences, and horticulture.

The money Macdonald donated to philanthropic causes was unparalleled in the history of Canada yet despite his wealth and good works, he remained a humble man who avoided publicity.