Britt Nichols was born in Gonçalo, Guarda, Portugal in 1950 as María do Carmo Ressurreição de Deus. Coming from a extremely impoverished home where many of her siblings passed away in childhood, she found a way out through the entertainment industry, first starting as a folk dancer, and then being noticed by modeling agents and filmmakers.

She made her first notable screen appearance as a human sacrifice to skeletal Templar zombies in Amando de Ossorio's atmospheric Tombs of the Blind Dead (1972), which was popular enough to spawn three sequels. Afterward, she appeared in major roles in seven exploitation films for director Jesus Franco, mostly in the horror genre. She had the titular role in Daughter of Dracula (1972), played a suspected witch in The Demons (1973) and played another bloodsucker in Dracula, Prisoner of Frankenstein (1972).