Cognomen ลำธาร (Brook 
, Rill 
, Creek ) , across the world, is a common family name. The cognomen ลำธาร is characteristic of Isle of Man, where it is quite a common surname, the United Kingdom, and Australia. Not in comparison with a country's population, it is commonest in the United Kingdom, the United States, and Australia. Likewise, ลำธาร is the forename as well as the last name.