David Thomson

"....[T]here is irony in Fontaine's having her greatest success as an interloper at a swank English household. This lady is very conscious of her own classiness. She may be a natural Rebecca, which makes her acting all the more praiseworthy. [I have had to remember than her character was not named "Rebecca"--dg.]

"Rebecca (40, Alfred Hitchcock) is an instance of film exploiting an audience's kindness toward an anxious performer. Fontaine won the nameless central role against tough opposition: Vivien Leigh, Margaret Sullavan, Anne Baxter, and Loretta Young. Several advisors to producer David Selznick were against Fontaine. Hitchcock was uncertain. But Selznick knew Fontaine; he had been smitten with her. He backed his hunch. And Hitchcock saw that the long-drawn-out casting procedure meant that she came to the part in the spirit that the character in Daphne du Maurier's novel comes to Manderlay--stricken with doubts, dowdy, hunch-shouldered, and a willing victim for the oppressive psychological forces that Mrs. Danvers had preserved in the house. Fontaine's ability to show that ordeal working on her is central to the film and a fine example of the concealed sadism Hitchcock brings to bear. It should also be said that Rebecca is a disguised horror film, with Fontaine at peril in an "old dark house." That peril seriously threatens her sanity, and the way she is drawn so near to suicide in teh window scene was a major, psychological intensification in Hitchcock's work.

Suspicion (41, Hitchcock) makes fewer demands on her, but of essentially the same sort. And if she won her Oscar for that, rather than for Rebecca, it may have been because Hollywood realized belatedly that a new female character had been introduced to the screen...."

David Thomson
A Biographical Dictionary of Film, 3rd edition (1994), P. 253
(revised slightly from 2nd edition, reprinted in 4th edition).