She held the titles of Infanta of Spain and of Portugal (since her father was king of Portugal as well as Spain) and Archduchess of Austria. Despite her Spanish birth, she was referred to as Anne of Austria because the rulers of Spain belonged to the senior branch of the House of Austria ,  known later as the House of Habsburg, a designation relatively uncommon before the 19th century.
She was named after her grandmothers, Empress Elisabeth of Austria and Queen Marie Henriette of Belgium. Erzsi was Franz Joseph's only grandchild through his son. In 1889, when Erzsi was a little over five years old, her father and Baroness Mary von Vetsera , his mistress, were found dead in what was assumed to be a murder-suicide pact at the Imperial hunting lodge at Mayerling .