Sasmuan is a fourth-class coastal municipality in the province of Pampanga, Central Luzon, Philippines. As of the 2020 census, it has a population of 29,076 people, making it the least populated municipality in the province. The town covers an area of 91.80 square kilometers and is situated along the coast of Manila Bay. It is bordered by Guagua and Minalin to the north, Macabebe to the east, Lubao to the west, and Manila Bay to the south.
Historically, Sasmuan was known as Sexmoán, a name derived from the Kapampangan word "sasmo," meaning "meeting place." The Spanish colonizers transcribed it as "Sexmoán," which later became a source of embarrassment due to its unintended connotations. In 1991, the name was officially changed to Sasmuan to better reflect its local heritage.