Sir William Curtius FRS, German magistrate, English baronet (d. 1678).
The Curtius Baronetcy of Sweden was a title in the Baronetage of England, created on 2 April 1652 for William Curtius, "Resident to the King of Sweden".Curtius was a diplomat representing the House of Stuart during the Thirty Years' War and the exile of Charles II, and head magistrate for two of the Electoral Palatinate districts for many years.

Curtius was elected as a Fellow of the Royal Society in 1667, and was England's Resident Ambassador to the Holy Roman Empire from 1664 until 1677.

The second baronet was Karl Wilhelm (Charles William); his son Carl August Adolf von Curti was the third.

The baronetcy became extinct in 1823 with the death of the fourth baronet, Wilhelm Adam. The Curti-Schloss was inherited by Julianne von Curti, and then by her children of her marriage into the Von Gall family.