|postal_code_type = ZIP code |postal_code = 76661 |area_code = 254 |blank_name = FIPS code |blank_info = 48-46740 |blank1_name = GNIS feature ID |blank1_info = 1362189 |website = http://www. marlintexas. com |footnotes = }} Marlin is a city in Falls County, Texas, United States. The population was 6,628 at the 2000 census. As of July, 2007, Marlin had an estimated population of 6,019, a -7.7% change from 2000. It has been the county seat of Falls County since 1851, the third different town to earn the title. Marlin alone as a county seat has had four different county courthouses.