Foundation and Empire is a science fiction novel by American writer Isaac Asimov originally published by Gnome Press in 1952. It is the second book in the Foundation series, and the fourth in the in-universe chronology. It takes place in two parts, originally published as separate novellas. The second part, "The Mule," won a Retro Hugo Award in 1996.

Foundation and Empire saw multiple publications—it also appeared in 1955 as Ace Double (but not actually paired with another book) D-125 under the title The Man Who Upset the Universe. The stories composing this volume were originally published in Astounding Magazine (with different titles) in 1945. Foundation and Empire was the second book in the Foundation trilogy. Decades later, Asimov wrote two further sequel novels and two prequels. Later writers have added authorized, and unauthorized, tales to the series.

Foundation and Empire is composed of two stories: "The General" and "The Mule". The former was first published in the April 1945 issue of Astounding Science Fiction under the title "Dead Hand", while the latter was first published in the November and December 1945 issues of the same magazine.

General Bel Riose of the Galactic Empire governs the planet Siwenna. He comes across myths regarding the Foundation and attempts to confirm them by coercing the aid of Ducem Barr, a Siwennian whose father Onum met the Foundation trader Hober Mallow decades ago. After further research through visiting Foundation territory, Riose determines that they are a threat to the Empire and declares war upon them, both to fulfill his duty to the Empire and satisfy his personal pursuit of glory. Barr is familiar with Hari Seldon's psychohistory and through it is confident of the Foundation's inevitable victory, an assertion Riose repeatedly disputes.

Riose captures and interrogates Lathan Devers, a Foundation trader who reveals in private to Barr that he allowed himself to be taken in order to disrupt Riose's operation from the inside. Devers is met by Ammel Brodrig, Emperor Cleon II's Privy Secretary who was sent to Riose in order to keep an eye on the general. Devers tries to implicate Riose in an attempt to overthrow Cleon. However, Brodrig betrays Devers to Riose. Barr knocks out Riose before he can subject Devers to more effective interrogation and Devers and Barr escape in the latter's ship. Barr only cooperated with Riose to prevent the discovery of a planned Siwennian uprising in the event of the Foundation's triumph over Riose.

Devers and Barr head to Trantor in an attempt at turning Cleon II against Riose by implicating the latter in a conspiracy to overthrow the former with the help of Brodrig. However, in their attempt to bribe their way up the chain of bureaucracy, they are caught in the act by a member of the Secret Police, but manage to flee the planet before they are arrested. During their escape, they intercept news of Bel Riose and Brodrig's recall and subsequent arrest for treason (both are later said to have been executed), which leads to Siwenna's rebellion and the end of the threat to the Foundation.

During the festivities celebrating Siwenna joining the Foundation, Barr explains to Devers and the Foundation's top merchant prince Sennet Forell that the social background of the Empire made the Foundation's victory inevitable regardless of what actions they and Bel Riose took, as only a strong Emperor and a strong general could have threatened the Foundation, but an Emperor is only strong by not allowing strong subjects to thrive, and Bel Riose's success made him into a threat that Cleon II needed to eliminate. With the Empire nearing its end and the Second Foundation not expected to be met until centuries later, the Foundation anticipates no further opposition. However, an internal conflict between the Foundation's merchant princes and the traders is foreshadowed.

Approximately one hundred years later, The Empire, after its final phase of decline and civil war, has ceased to exist, Trantor has suffered "The Great Sack" by a "barbarian fleet," and only a small rump state of 20 agricultural planets remain. Most of galactic civilization has disintegrated into barbaric kingdoms.