Yechezkel ben Yehuda Landau was an influential authority in halakha (Jewish law). He is best known for the work "Nodah bi-Yehudah" (נודע ביהודה), by which title he is also known. Wikipedia
I. Rabbi Ezekiel Landau, also known as the "Noda Biyehudah," after the title of his major work, was born in Opatow, a small town in Poland. www.chabad.org/library/article.asp?AID=111912
One evening the Noda B'Yehuda, Rav Yechezkel Halevi Landau, was walking to shul when he noticed a young, non-Jewish peddler sobbing uncontrollably. www.famousrabbis.com/noda.htm
Rabbi Yechezkel Landau was born in 1713 in Opatow, Poland , and received his Rabbinical education in Galicia. www.jewishvirtuallibrary.org/jsource/biography/Landau1.html
The definitive Wikipedia entry for Yechezkel Landau. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Yechezkel_Landau