《源头》（英文：The Fountainhead），又译为《源泉》，是一本由美国哲学家和小说家艾茵·兰德撰写的哲学小说，最先在1943年出版。此书为兰德的第一本主要的成功小说、也是她最畅销的小说之一，她总共花了7年时间撰写这本小说。小说曾被12家出版商拒绝，他们认为那太过智能而违背当时美国思想的主流。最后小说终于被Bobbs-Merrill出版公司接受，发行于1943年，这主要是因为出版社编辑群中的一名成员Archibald Ogden大力推荐这本书（「如果这本书不适合你，那我也不是适合你的编辑。」），出版后，口碑很好，获得空前的成功。《源头》一书不只在美国、也在世界性获得了胜利，带给兰德前所未有的名声和财富。在出版后的第6年里，这本小说已经卖出六百万本，最后继续保持每年卖出100,000本的纪录。

The Fountainhead is a 1943 novel by Ayn Rand, and her first major literary success. More than 6.5 million copies of the book have been sold worldwide.

The Fountainhead's protagonist, Howard Roark, is an individualistic young architect who chooses to struggle in obscurity rather than compromise his artistic and personal vision. The book follows his battle to practice what the public sees as modern architecture, which he believes to be superior, despite an establishment centered on tradition-worship. How others in the novel relate to Roark demonstrates Rand's various archetypes of human character, all of which are variants between Roark, the author's ideal man of independence and integrity, and what she described as the "second-handers". The complex relationships between Roark and the various kinds of individuals who assist or hinder his progress, or both, allow the novel to be at once a romantic drama and a philosophical work. Roark is Rand's embodiment of what she believes to be the ideal man, and his struggle reflects Rand's personal belief that individualism trumps collectivism.