William McNeill was born in Lower Montague, Prince Edward Island and was educated at Acadia University and Harvard. After teaching at Bates College for three years, he returned to Harvard where he earned a PhD in English in 1909.
He joined Queen's English Department the same year as an Assistant Professor and quickly gained a reputation as a precise scholar. He served as acting department head in 1913-14 and was appointed department head in 1920, but only held the position for three weeks. Former principal Daniel Miner Gordon convinced the Board of Trustees that McNeill was a dull and uninspiring teacher and persuaded them to move him to the recently vacated position of Registrar and Treasurer.
It was a humiliating blow for McNeill, who never wanted to be anything but a scholar, but he buried his humiliation in work and soon demonstrated an unusual talent for administration and financial management. He proved himself so indispensable to the university that he was appointed Vice-Principal in 1930, but still held the position of Treasurer as well. Between 1930 and 1936, during the Principalship of William Hamilton Fyfe, McNeill virtually ran the university because Fyfe disliked administrative duties.
He urged the Trustees of Queen's to safeguard the University's endowment, and his wisdom was applauded during the Depression. He was known for his penny-pinching during these lean years, and although many resented his strict financial control, the Queen's community was proud of the fact that it did not reduce salaries during the Depression as most other universities did. McNeill produced a balanced budget every year, and somehow managed to cut $100,000 from expenditures. He was known to count packets of 1000 envelopes to check if they were all there, and to turn down a professor's request for a pencil sharpener because there was already one on another floor in the same building.
It was largely to his credit that Queen's survived the Depression without drastic cutbacks. He remained Vice-Principal and a powerful figure at Queen's until his retirement in 1947, after which he served on the Board of Trustees.
McNeill House is named in his honour.
McNeill is buried in the Cataraqui Cemetery.