MacWilliams and MacWilliam are English-language surnames. They are derived from the Gaelic Mac Uilleim, a patronymic form of a Gaelicized form of the English William. The final -s in MacWilliams is a redundant English patronymical suffix.
Dave MacWilliams (born 1957), American soccer player Jessie MacWilliams (1917–1990), English mathematician Keenan MacWilliam (born 1989), Canadian actress Lyle MacWilliam (born 1949), Canadian congressman Mike MacWilliam (born 1967), Canadian ice hockey player
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