Karl was born in Vienna, Austria-Hungary, the youngest son of Archduke Leopold Salvator of Austria (1863–1931) and of his wife Infanta Blanca of Spain (1868–1949).
Karl was born in Vienna, Austria-Hungary, as the youngest child of Archduke Leopold Salvator of Austria (1863–1931) and his wife Infanta Blanca of Spain (1868–1949).