Levi'im (Levites), descended paternally from the Jewish tribe of Levi; the forerunner of the Landau family is Rav Yehuda Liva, who lived in the 14th century in the German town of Landau. His son, Rav Yaakov Boruch, the rishon who wrote the sefer "Ha'agur," quotes his father throughout his responsa. Many Landaus are descended from the famous 18th Century Rabbi, Talmudist and scholar the Gaon Rav Yechezkel Landau zt’l, known as the ‘Noda B’Yehudah’ after his major work of that name. He was born (in the Jewish calendar) on the 18th of Cheshvan in the year 5474 (Oct. 8th 1713) in the town of Apta in Poland to an eminent family that traced its lineage back to the 11th century medieval French Rabbi, Talmudist, Biblical commentator and scholar Rabbeinu Shlomo Yitzchaki – Rashi, himself a descendant of King David. The Noda B'Yehudah is best known, other than through his works which are still of major significance in Jewish scholarship, as the influential Rabbi of Prague during a tumultuous period in the history of both the city and its Jewish community for a period of 38 years until his death in 1793.
Following taken from https://www.chabadhackensack.com/library/article_cdo/aid/5198012/je...
The Jewish family name Landau can be traced to the town of Landau in der Pfalz, in the heart of Germany’s wine country, not far from the French border. The city had a Jewish community that lasted from the 12th century until the Holocaust.
Fun fact: In addition to many prominent (and not so prominent) Jews, the city also lent its name to a certain horse-drawn carriage with a retractable fabric roof, which is still used by the British royal family.
Many Landaus trace their lineage to Rabbi Yehuda Landau, the city’s rabbi. Some of his descendants traveled south, founding the Italian branch of the family. In time, they headed east, to Moravia and Poland.
Since the “au” sound is not easily pronounced by many Eastern-European Jews, who would more easily recognize לנדוי as “lan-doy,” the name has often been modified to Landa (לנדא) or Lando (לנדו).
Perhaps the most famous member of the Landau family is Rabbi Yechezkel HaLevi (Segal) Landau, Chief Rabbi of Prague, known by the name of his major Halachic work, the Node BiYehudah.
In modern times, the name has been closely associated with three successive generations of Landas who have served as Chief Rabbis to the city of Bnei Brak in Israel. The first, Rabbi Yaakov Landa (1893-1986), was previously the in-house rabbi for the household of the fifth Rebbe, Rabbi Sholom Dovber Schneersohn. Under the leadership of his son, Rabbi Moshe Yehuda Leib Landa (1935-2019), the Landa name became synonymous with high-level kosher certification, as he (like his father) provided his stamp of approval at no cost to any company willing to comply with his exacting requirements. Their legacy is continued by Rabbi Isaac Landa.
Today, the Landau family tree has fruitful branches (some Levites, and others who are not) in Israel, the US, Europe, and virtually everywhere else Jews live.