Elaine de Francias, Comtesse de Montmorency (1557–1625) was the illegitimate daughter of Henry II of France and Catherine Michelle.
Supposedly Henry questioned whether or not to give her a title and it was not until his deathbed that he admitted to her being his. After this confession he gave her the title Countess of Montmorency. It is questioned as to why he was so secretive about this one daughter by Catherine Michelle.
However others do not question his youngest daughter's mystery as he supposedly thought that she possessed powers of a witch and would curse him, as he soon fell ill and died a year after her birth. She was burnt at the stake, but not before producing another two illegitimate children from her own half brother Henry III, King of France, one of which died at birth: Jane de Francias and Nicola de Montague (1576)–(1631).