Jan Kazimierz Umiastowski (died 1659) was a Polish szlachcic from family - comites Pierzchała-Umiastowski. He was District Writer of Brześć since 1648, District Judge and Podkomorzy (Chamberlain) of Brześć; since 1654. Marshal of the Sejm (nadzwyczajnego) on May 19, - June 20, 1655 in Warsaw. Year of birth unknown 1659 deaths 17th-century Polish nobility Jan Kazimierz