Opus 300 is a collection by American writer and scientist Isaac Asimov. It was published by Houghton Mifflin in the United States in 1984, and by Robert Hale Ltd in the United Kingdom in 1985. Asimov chose to celebrate the publication of his three hundredth book by writing about his previous 99 books, including excerpts from short stories and novels, as well as nonfiction articles and books. Opus 300 also includes nine complete stories, several complete science essays, and one complete essay never before published, "The Forever Generation," which is not available anywhere else.