Neotrantor was a small agricultural planet located near the center of the galaxy, near Trantor. After the Great Sack, it was the location of the last seat of the Galactic Empire. Dagobert IX short reign stemmed from Neotrantor.
In Foundation and Empire, Toran and Bayta Darell, Ebling Mis, and the Mule visit Neotrantor during their search for the Second Foundation. They are given permission by Dagobert IX to enter the Imperial Library on Trantor, but are stopped by Dagobert X, who wishes to marry Bayta. After the Mule kills the crown prince, the group leaves the disenfranchised Neotrantor.