William McMaster (1811–1887) was a Canadian wholesaler, senator and banker.
William McMaster may also refer to:
William Alexander McMaster (1879–1961), Canadian parliamentarian and lawyer William H. McMaster (1877–1968), governor of South Dakota William McMaster (businessman) (1851–1930), Canadian businessman William McMaster Murdoch (1873–1912), Scottish sailor who served as first officer aboard the RMS Titanic