Hugh Cowie Williams (born 23 July 1943) is a Canadian mathematician.

Williams studied mathematics at the University of Waterloo (bachelor's degree 1966, master's degree 1967), where he received his doctorate in 1969 in computer science under Ronald C. Mullin and Ralph Gordon Stanton (A generalization of the Lucas functions).

Since 2001 he has held the "iCore Chair" in Algorithmic Number Theory and Cryptography.

In it, he showed among other things that Édouard Lucas worked shortly before his early death on a test similar to today's elliptic curve method.

[6] Together with Jeffrey Shallit and François Morain he discovered a forgotten mechanical number sieve created by Eugène Olivier Carissan, the first such device from the beginning of the 20th century (1912), and described it in detail.