Spanish Princess Maria Teresa de Borbon-Parma, 86, died in Paris on Thursday after contracting the novel coronavirus, her brother announced on Sunday.
A member of the Carlist branch of the Bourbon dynasty, she became the first royal to fall victim to the pandemic that has gripped Europe for weeks, Turkey-based news agency Anadolu Agency reports.
Known as the Red Princess for her relatively leftist views, Borbon-Parma worked as a Sociology professor at Sorbonne University in Paris and rarely used her royal title.
"Throughout her life she held a diplomatic attitude that was far from dynastic, in a way she was progressive, separating herself from the traditionalist principles of her younger brother Sixto," read an obituary in Spanish daily La Vanguardia.
Earlier this week, the 71-year-old Prince Charles tested positive for the coronavirus in the UK.
Spain's royal family has also been tested, but all their results came back negative.