Kotarszyn [kɔˈtarʂɨn] is a village in the administrative district of Gmina Waśniów, within Ostrowiec County, Świętokrzyskie Voivodeship, in south-central Poland. It lies approximately 5 kilometres (3 mi) north-west of Waśniów, 15 km (9 mi) west of Ostrowiec Świętokrzyski, and 42 km (26 mi) east of the regional capital Kielce.