Yang Berhormat Tuan Lau Weng San (Chinese: 刘永山; pinyin: Liú Yǒngshān; born 12 February 1978) is a Malaysian politician and engineer who has served as 12th Speaker of the Selangor State Legislative Assembly since September 2023.

He served as Member of the Selangor State Legislative Assembly (MLA) for Banting from May 2018 to August 2023 and for Kampung Tunku from March 2008 to May 2018.

Lau won the seat and was elected to the Selangor State Legislative Assembly as the Kampung Tunku MLA for the first term after defeating Sheah Kok Fah of Barisan Nasional (BN) by a majority of 7,977 votes.

Lau defended the seat and was reelected to the Selangor State Legislative Assembly as the Kampung Tunku MLA for the second term after defeating Kelvin Chong Seng Foo of BN by a majority of 13,685 votes.

Lau won the seat and was reelected to the Selangor State Legislative Assembly as the Banting MLA for the first term after defeating Ng Siok Hwa of BN and Philip Tan Choon Swee of Parti Rakyat Malaysia (PRM) by a majority of 17,299 votes.