Olędrzy (Polish: [ɔˈlɛndʐɨ], Singluar form: Olęder; German: Holländer, Hauländer) were people, often of Dutch or German ancestry, who lived in settlements in Poland organized under a particular type of law.
The term Olędrzy has been used to describe two related, but slightly different, groups of settlers. First, it describes settlers in Poland from Friesland and the rest of the Netherlands, most often of the Mennonite faith, who in the 16th and 17th centuries founded villages in Royal Prussia, along the Vistula River and its tributaries, in Kuyavia, Mazovia and Greater Poland. They possessed knowledge of flood control, and a well-developed agrarian culture. At that time, they were the wealthiest group of peasants. They maintained personal freedom, and their own religion and beliefs. After the First Partition of Poland, some of them emigrated to Ukraine.
Second, in a later period (up to the middle of the 19th century), the term Olędrzy was used to describe settlers of different ethnicities (principally Germans and Poles, at times Scots, Czechs, and Hungarians), who benefited from certain privileges resulting from the law established by the Frisian and Dutch colonists (such as personal freedom, long-term or perpetual use of land, and the possibility of transmitting land to heirs). The most important characteristic, however, was collective responsibility of the entire Olęder community for its obligations toward the land owner and the specific character of the community's self-government. Thus, the distinguishing characteristics of an Olęder settlement are legal, and not ethnic, religious or economic. Consequently, the word Olęder is not synonymous with "Dutch settler."