小说《五十度灰》由中年女作家E-L-詹姆斯（E.L.James）创作，《五十度灰》最初发表在互联网上，当时叫做《宇宙之王》（MaseofheUivese），是一篇受《暮光之城》启发创作的同人文小说（FaFicio），由于大受欢迎，2011年5月被出版成书。《五十度灰》还有两部续集，分别是《FifyShadesDake》和《FifyShadesFeed》，其电影版权同样被环球公司和焦点公司获得。
50度灰英文版最新章节（2个月前更新）
Part III Chapter Twenty-five
Part III Chapter Twenty-four
Part III Chapter Twenty-three
Part III Chapter Twenty-two
Part III Chapter Twenty-One
Part III Chapter Twenty
Part III Chapter Nineteen
Part III Chapter Eighteen
50度灰英文版全部章节目录（共61章）
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Part 1__2
Part 1__3
Part 1__4
Part 1__5
Part 1__6
Part 1__7
Part 1__8
Part 1__9
Part 1__10
Part 1__11
Part 1__12
Part 1__13
Part 1__14
Part 1 15
Part II 1
Part II 2
Part II 3
Part II 4
Part II 5
Part II 6
Part II 7
Part II 8
Part II 9
Part II 10
Part II 11
Part II 12
Part II 13
Part II 14
Part II 15
Part II 16
Part II 17
Part II 18
Part II 19
Part II 20
Part III
Part III Chapter One
Part III Chapter Two
Part III Chapter Three
Part III Chapter Four
Part III Chapter Five
Part III Chapter Six
Part III Chapter Seven
Part III Chapter Eight
Part III Chapter Nine
Part III Chapter Ten
Part III Chapter Eleven
Part III Chapter Twelve
Part III Chapter Thirteen
Part III Chapter Fourteen
Part III Chapter Fifteen
Part III Chapter Sixteen
Part III Chapter Seventeen
Part III Chapter Eighteen
Part III Chapter Nineteen
Part III Chapter Twenty
Part III Chapter Twenty-One
Part III Chapter Twenty-two
Part III Chapter Twenty-three
Part III Chapter Twenty-four
Part III Chapter Twenty-five