Valak

In Romania, a duke opened a gateway to hell in the castle that later became the Cârța abbey. It was sealed with the blood of Christ, but a World War II bombing broke it open again. The nuns prayed day and night to hold Valak back.

In 1952, it gets out, takes the form of a nun and attacks Father Burke and Sister Irene. Irene drives it out with the relic. But it leaves the abbey hidden inside Frenchie, the guide, who ends up with an inverted cross on his neck. Twenty years later, the exorcism of Frenchie, whose name is Maurice, turns up at a Warren lecture.

Valak shows up briefly in a photo Sister Charlotte keeps of her old convent in Romania, in the background, among the other nuns. It's a quick nod: nobody at the Mullins house notices the figure, but it shows the demon was already close by.

In 1956, still inside Maurice, Valak crosses Europe killing clergy. A priest is burned alive in a French church, and more deaths follow the same trail. It's after the eyes of Saint Lucy, a relic that would make it stronger, hidden at a boarding school in Tarascon, France.

Irene faces it again. She turns a vat of wine into the blood of Christ and Valak is destroyed, at least for a while. Along the way, it also uses another shape to scare the girls at the school: a goat-like demon. Maurice is freed and survives.

In 1976, Valak appears to Lorraine Warren at Amityville and shows her Ed dead. In 1977, in Enfield, it uses old Bill Wilkins' spirit to torment Janet Hodgson and hide that it's behind everything.

The plan falls apart when Lorraine finds its name, which she wrote in her Bible during a vision. She says "Valak" and sends it back to hell. A painting of Valak that Ed made after a dream also helps tie the nun to the case.

Valak doesn't come from a Warren case. The name comes from the Ars Goetia, a 17th-century grimoire that lists demons. James Wan created the nun form for The Conjuring 2, and Bonnie Aarons has played it ever since.