For Kim Novak I have nothing but praise

James Stewart and Kim Novak starred together in two films, i.e. in Alfred Hitchcock's Vertigo (1958) and the fantasy comedy Bell, Book and Candle (1958). The actors got along very well, and Novak later said that Stewart was her "all-time favorite man, next to [her] husband" and "the best, nicest person [she] ever worked with". According to filmmaker Peter Bogdanovich, the two had an affair during Vertigo which continued through Bell, Book and Candle. When author Marc Eliot asked Novak about it —while doing research for his 2006 biography on James Stewart— she categorically denied the affair. "She said she had been in love with Richard Quine, the director of Bell, Book and Candle", said Eliot. "She added that Jimmy was married, and there was no way that she would have an affair with a married man." 

In 1980, Larry Kleno published his book on Kim Novak, entitled Kim Novak on Camera. In preparation for the book, Kleno contacted several of Novak's co-stars, asking them how they had experienced working with her. Naturally he also got in touch with James Stewart, who sent the requested information via the following letter:

Source: Bonhams

Above clockwise: James Stewart and Kim Novak in Vertigo, in a scene from Bell, Book and Candle and on the set of Vertigo.