Bourbon claim to the Spanish throne
After the death of the last Habsburg monarch of Spain in 1700, the childless Charles II, the Spanish throne was up for grabs between various dynasties of Europe despite Charles having left a will naming his heir. In this will, Charles left the French prince Philip, Duke of Anjou, grandson of Louis XIV, the possessions of the Spanish Crown.
Source: Wikipedia — Bourbon claim to the Spanish throne (CC BY-SA 4.0)