The Fastest Serve in Women's Tennis

According to Wikipedia, "[Venus] Williams held the record for the fastest serve in women's tennis at 207.9 km/h (129.2 mph), achieved at the 2007 US Open. She held this record for almost 7 years, until her record was broken by Sabine Lisicki at the 2014 Stanford Classic with a service speed of 210.8 km/h (131.0 mph)."

Lisicki still holds the official WTA record, but two players have served faster in matches that the WTA doesn't recognise for this purpose. Aryna Sabarenka of Belarus (currently ranked No. 74 in the world) served at 214.0 km/h (133.0 mph) in the 2018 WTA Elite Trophy (30 October to 4 November), but the current unofficial record is held by Georgina García Pérez of Spain (currently ranked No. 90 in the world) who served at 220.0 km/h (136.7 mph) in the 2018 Hungarian Ladies' Open (19–25 February).

Even when Venus Williams set the official record, there was a faster serve that was not recognised. In the 2006 Cincinnatti Masters, Brenda Schultz–McCarthy, of the Netherlands, served at 209.2 km/h (130.0 mph). This is currently the fourth fastest serve on record.

The WTA only recognises speed records that are set within the selected main draw segment of WTA Tour tournaments, where at least one of the courts has a speed gun installed. Records that have been achieved during qualifications in those same places, as well as those documented at other matches (including ITF tour events, Fed Cup ties, and the Olympics) do not count.

The unofficial record for the fastest serve in man's tennis is currently held by Sam Groth of Australia. In the 2012 Busan Open Challenger tournament (in South Korea), Groth's serve was recorded at 263 km/h (163.4 mph). Sam Groth retired in 2018; his highest world ranking was 53rd, in 2015.

The official fastest serve in men's tennis (recognised by the ATP) is currently 253 km/h (157.2 mph) by John Isner of the USA, achieved in the 2016 Davis Cup. Isner is currently ranked No. 10 in the world.

Except for the first paragraph, this information is from Wikipedia's Fastest Recorded Tennis Serves page.