Karl Prince of Isenburg Budingen
- Category : 1838-births
- Type : MGE
- Profile : 4/6 - Opportunistic / Role Model
- Definition : Triple Split
- Incarnation Cross : RAX Unexpected 2
Prince of the mediatised German house of Isenburg and Büdingen. He was the second child of Victor Alexander, Prince of Isenburg-Büdingen, son of Karl, last sovereign Prince of Isenburg, and his wife, Princess Maria of Löwenstein-Wertheim-Rosenberg.
On 31 May 1865, at the age of twenty-seven, he married Archduchess Maria Luisa of Austria-Tuscany (1845–1917), daughter of Leopold II, Grand Duke of Tuscany and his second wife, Princess Maria Antonia of the Two Sicilies. The couple had nine children. In 1866, after the death of his uncle, Karl succeeded him as Prince of Isenburg-Birstein.
Karl died at the age of sixty on 4 April 1899.