Kasper Doenhoff was a Polish noble (szlachcic) of the Denhoff coat-of-arms; he was born a member of the Denhoff family, a Polish noble family of East Prussian origin (the German family name is Dönhoff).
In the Holy Roman Empire, he was a noble (Reichsfürst); count (from 1635); prince (from 1637); and court marshal.