Samuel Ludwik Zasadius or Zasadyus, Sassadius (ca. 1695–1756) was a Polish religious writer and pastor. Author of popular sermons, prayer-books. Also known for propagating Polishness in Cieszyn Silesia.
Zasadius was born ca. 1695 in Komorzno as a son of Polish pastor. He studied in Wittenberg and Jena. In the years of 1721–1730 Zasadius was a deacon and preacher of Jesus Church in Cieszyn.
He led educational activity, published Polish magazine and learned Polish language. In 1730 expelled (with pastors Johann Adam Steinmetz and Jan Muthmann) from Austrian monarchy for being favour with Pietism movement. He stayed in Germany until 1742. After coming back, became a pastor in Tarnowskie Góry. He died there on March 25, 1756.
Zasadius is an author of popular prayer-books and song-books, such as Mleczna potrawa duchowa... (1726), catechism Droga do nieba... (1723), collection of orations Kazania pokutne (1730). He translated a New Testament (1725), The Small Catechism by Martin Luther (1727) and other Luther works.
Further reading 
- Golec, Józef; Bojda, Stefania (1993). Słownik biograficzny Ziemi Cieszyńskiej (in Polish). vol. 1. Cieszyn: Nakład autorów. OCLC 69547117.
- Bednarczyk, Ryszard (October 26, 2007). "Natchniony polskim duchem". Gwarek (wydanie internetowe) (in Polish).