Samuel Ludwik Zasadius or Zasadyus, Sassadius (ca. 1695–1756) was a Polish religious writer, pastor and author of popular sermons and prayer-books. He was also known for propagating Polishness in Cieszyn Silesia.
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.