I have always thought, additionally, that without the casting of Heather Donahue in the role of the female lead, with her particular sincerity, the churchiness of her voice, and the way she channels her terror and dismay (controlling it only for so long, before letting it overwhelm her), that this movie would not have achieved its identity, nor its iconic stature, for she seems to me irreplaceable in a way that actors and actresses in low-budget, independent movies do not always seem, even when the movies are exceptional.