Charles Kwan Siu-Cheung (Traditional Chinese: 關兆昌, born September 3, 1963) is the most successful Hong Kong racing driver who has competed in the Macau Guia Race, Japan GT Championship, FIA GT Championship, Porsche Carrera Cup Asia, South East Asia Touring Car Zone Challenge (SEATCZC) and the Asian Touring Car Championship. He was the winner of the 1993 Guia Race, three times SEATCZC champion and the 2003 Porsche Carrera Cup Asia champion. He also performed roadtests and wrote columns for car magazines in Hong Kong.

Kwan first came to prominence, after winning numerous supporting races in prior years, he won the Guia Race in 1993 in a DTM spec BMW M3 and two other races on the same weekend (one was the Supercar Challenge in a Porsche 911 and CTM Cup race). In the Supercar Challenge in 1994, he was the first driver to give the Ferrari F355 its first win on its race debut and for the following year, it was a Ferrari F50 he repeated the feat.

Charles Kwan shared a BMW M3 at Team Over Take with fellow Hong Kong drivers Kevin Wong and Macau driver Winston Mak in the 1992 Japanese Touring Car Championship.

In 1994, he competed in the South East Asian Touring Car Zone Challenge (SEATCZC), driving a BMW M3 for Three Crowns Racing. In the Zhuhai street race supporting the BPR Global GT Series, Kwan had qualified his BMW M3 second on the grid. Right at the race start, both Kwan and fourth place starter Henry Lee Junior were hit by Thailand's S. Prutirat and Man Manit, who drove Mercedes Benz 190Es for AIM Motorsport and were on pole position and third place. Both Kwan and Lee retired as a direct result. In a 2006 interview with Car Plus magazine, Kwan said he still considers that to be his most memorable race, due to the unsporting behaviour against him.

Kwan went on to become a three-time champion of the SEATCZC from 1997 to 1999, driving a Super Touring BMW 318i for EKS Motorsport and sponsored by Total/Fina.

Also in 1994, Kwan was sponsored by San Miguel Corporation in the Macau Guia Race and became the first Chinese driver to drive for Schnitzer Motorsport, alongside regular drivers Steve Soper and Joachim Winkelhock in the team's BMW 318is. The race was also a round of the Asia-Pacific Touring Car Championship. In the end, Kwan finished fifth overall as Winkelhock won and Soper finished second. He would continue to drive for Schnitzer in the next few years.

The SEATCZC became the Asian Touring Car Series in 2000 as the series changed to use Super Production regulations. WK Longman Racing joined the series with their duo of Peugeot 306 race cars, to be driven by Henry Lee Jr and C. Nattavude, with support from engine tuner Richard Longman in the UK.

Charles Kwan stayed with EKS Motorsport and the team entered two BMW 320is for the season, one for Kwan and one for Paul Chan. Kwan drove one of his most memorable races at the Batu Tiga Speedway at Shah Alam this year. His engine had broken down during practice. Although his teammate Paul Chan kindly lent him his engine for the race, the engine replacement work meant Kwan did not take part in qualifying and had to start the race from the back of the grid. Despite this, he passed all the drivers in front of him to claim the victory.