The Lightning and the Sun is a 1958 book by Savitri Devi, in which the author outlines her esoteric Hitlerist philosophy of history along with her critique of the modern world. The book is known for the author's claim that Adolf Hitler was an avatar of the Hindu god Vishnu and its cyclical view of history, which Savitri Devi intertwines with Nazism. It portrays Hitler as a "Man against Time", exhibiting both "Lightning and Sun" qualities: in Devi's worldview, destruction used for life-affirming purposes.

Devi began writing the book in 1948 in Scotland, ultimately completing it in Germany in March 1956. It was initially self-published by Devi in 1958 in Calcutta, India, financed by Devi's job as an interpreter. The book was obscure for several years, until 1966, when an abridged version was published by William Luther Pierce in the neo-Nazi magazine National Socialist World. The 1966 republication exposed the book to a worldwide demographic of neo-Nazis and popularized it among them. The neo-Nazi publishing house Samisdat Publishers, operated by Ernst Zündel, issued a new illustrated edition in 1979. The book was excerpted in Adam Parfrey's 1987 anthology Apocalypse Culture.

Described by scholars as Devi's most significant work, The Lightning and the Sun was greatly influential on neo-Nazis internationally and continues to be popular with the far-right. It has since been republished by a variety of neo-Nazi and white nationalist publishing houses, including National Vanguard Books, Counter-Currents Publishing, and Kerry Bolton's Renaissance Press. It introduced esoteric neo-Nazism to a wider audience of white supremacists; among the figures the work has influenced are David Myatt, Miguel Serrano, and William Luther Pierce.