Feliksa Kozłowska (also known as Felicja Kozłowska and Sister Maria Franciszka) (May 27, 1862, Wieliczna - August 23, 1921, Płock) was a Polish religious mystic and visionary who founded what eventually became the Old Catholic Mariavite Church, and, by implication, a dissident group which split from it in 1935, the Catholic Mariavite Church.
Tribus Circiter is an encyclical of Pope Pius X on the Mariavites or Mystic Priests of Poland, a pseudo-monastic Polish society founded by Feliksa Kozłowska, which later broke away from the Catholic Church to become the Mariavite Church.