Sansiri (Thai: แสนสิริ) is one of the largest real estate developers in Thailand. It was founded in 1984 by Srettha Thavisin, Apichat Chutrakul, and Wanchak Buranasiri.

Sansiri was founded as the holding company to manage the assets of the Chutrakul family, before merging with the Lamsam family company in 1994. The company has been listed on the Stock Exchange of Thailand since 1996. In its earlier years, the company concentrated on developing exclusively mid-city condominiums for sale and for rent. In 1998, the company expanded into property management and sales management services through the newly founded subsidiary named Plus Property Company Limited. In 1999, the company underwent a major expansion into development of landed properties with the launch of the first single-detached housing project.