Desmond Rex Williams BEM (born 20 July 1933) is an English retired professional billiards and snooker player.

He was the second player to make an official maximum break in snooker, achieving this in an exhibition match in December 1965.

Williams won the World Professional Billiards Championship from Clark McConachy in 1968, the first time that the title had been contested since 1951.

[5] In 1951, at 17 years old, he became the youngest winner of the English Amateur Snooker Championship (until Jimmy White in 1979), beating the 1939 champion Percy Bendon 6–1 in the final.

[8] Williams made his debut at Leicester Square Hall in early 1952, playing John Pulman in an exhibition match on level terms.

[11][12] In May and early June 1952, Williams played in the qualifying competition for the 1952/1953 News of the World Snooker Tournament.

[17] Williams met Harry Stokes in the 31-frame qualifying round of the World Championship in early October 1953 and led 3–2 after the first session.

[21]: 8 [22] Williams was instrumental in the revival of the World Snooker Championship in 1964, obtaining sanction for the competition after taking the Billiards Association and Control Council (BA&CC) chairman Harold Phillips out to lunch.

[30] In December 1965, during an exhibition match in Cape Town against Mannie Francisco, Williams followed Joe Davis as the second man to make a recognised 147 break.

[4][31] In 1967, Williams and Fred Davis played a 51 match series that was billed as the World Open Matchplay Snooker Challenge, even though no other entries were solicited.

The championship then reverted to a knockout format, and was held in November 1980, with Williams losing to Mark Wildman in the semi-final.

There were no rules in place for penalties for late arrivals, but following complaints to the WPBSA, Williams was fined £500 by the association, and resigned as chairman, but remained on the board.

[2][33] In 2001, he was expelled from the Association following alleged fiduciary irregularities and asked to repay legal costs of £28,268,[42] but was reinstated as a full member the following year.

[43] Williams reached the semi-final of the World Snooker Championship three times, losing to John Spencer in 1969, in 1972 to Alex Higgins 30–31 (having been four frames ahead with five left to play) and, in 1974, 7–15 to Graham Miles.

[48] During the 1986–87 snooker season, Williams became the oldest player to reach a world-ranking final when, aged 53, he lost 6–10 to Jimmy White at the 1986 Grand Prix, after having led 6–4.

His run to the Grand Prix final included 5–1 wins over both Higgins and Steve Davis, and a 9–8 semi-final defeat of Neal Foulds.

[21]: 82 [49][50]: 41–42 [44] His last tournament as a professional snooker player was the 1995 World Championship, where he beat Steve Day and Chris O'Sullivan, before losing in the fourth qualifying round 3–10 to Nick Walker.

[51] He founded a cue-making company, Power Glide Cues, and in 1975 established Rex Williams Leisure, a snooker and pool table manufacturing and hire business.

Stephen Hendry bought a Rex Williams signature cue for £40 when he was aged 13, and used it until it was broken in 2003, including during his seven world snooker championship wins.