The Galactic Empire series (also called the Empire novels or trilogy) is a science fiction sequence of three of Isaac Asimov's earliest novels, and extended to one short story. They are connected by their early place in his published works and chronological placement within his overarching Foundation Universe, set around the rise of Asimov's Galactic Empire, between the Robot and Foundation series to which they were linked in Asimov's later novels.
In order of internal chronology the Empire series consists of:
These stories are set in the same future as the Foundation series, which had appeared in magazines starting in 1942. The tie is not close, and they are only loosely connected to each other, each being a complete tale in its own right. Their main common points are Asimov's idea of a future Galactic Empire, certain aspects of technology — hyperdrive, blaster pistols, "neuronic whips," the possible invention of the "Visi-Sonor" — and particular locations, such as the planet Trantor?. Another connection was later established with Robots and Empire, where Asimov revealed how Earth became radioactive, as mentioned in all three novels. Some sources further this argument by asserting that The Stars, Like Dust takes place about one thousand years following the events of Robots and Empire?. Also, the calendar used on spaceships in The Stars, Like Dust is the same that the Spacers introduce Lije Baley to in The Robots of Dawn.
The short story "Blind Alley" is the only story set in the Foundation universe to feature intelligence not of human origin; Foundation and Earth features non-human intelligences (of Solaria? and Gaia?), but they are descended from or created by humans.
Asimov later integrated them into his all-engulfing Foundation series. Some contortion was required to explain how the robots of the Robot series are almost completely absent from the Galactic Empire novels. In reality, this is because Asimov wrote the original Robot and Foundation short stories as separate series.