Sir William Peterson, K.C.M.G. (29 May 1856 – 4 January 1921) was a Scottish academic and the Principal of McGill University from 1895 to 1919.

Born in Edinburgh, the fifth son of John Peterson and Grace Mountford Anderson, Peterson graduated from the University of Edinburgh in 1875 and Corpus Christi College, Oxford in 1879. In 1882, he became the first Principal of University College, Dundee. From 1895 to 1919, he was the Principal of McGill University in Montreal, Canada.

In 1915, he was created a Knight Commander of the Order of St Michael and St George.

In 1919, he returned to England and died at Hampstead in 1921.