Wojciech Kętrzyński (11 July 1838 – 15 January 1918), born Adalbert von Winkler was a historian and the director of the Ossolineum Library in Lviv, Austrian Empire. He focused on Polish history at a time when Poland was partitioned between foreign powers. He was the father of Stanisław Kętrzyński.
The Kętrzyński-family is of Kashubian origin and settled in Pomerania since the sixteenth century. In 1821 his father had changed his surname to "von Winkler", a direct translation of "Kętrzyński", while he served in the Prussian Army. After he left the military his father became a Prussian policeman (gendarm) at Lötzen where he married a local German wife and died in 1846.
Kętrzyński was born in Lötzen (Lec, modern Giżycko) as Adalbert von Winkler, Province of Prussia, within the Kingdom of Prussia, and grew up under the care of a German family after his father's death. He was sent to a military school for soldier orphans at Potsdam in 1849 but returned to Masuria and passed his Abitur at Rastenburg (Rastembork, modern Kętrzyn). In 1856 his sister had discovered the family's ancestry and informed him about it, which caused his decision to identify himself as a Pole, even though he did not read or write Polish and knew only a few words and expressions. As Kętrzyński later wrote, at the time of his national conversion he "was a German and felt himself to be German" and this "decision had been sudden and had raised no doubts". In 1859 he enrolled at the University of Königsberg, still as "von Winkler", but used the name "von Kętrzyński" for his matriculation in 1861. Here he also spoke for the first time Polish to students.