Gaal Dornick was a mathematician born on Synnax in the 13th millenium GE. In 12,067, shortly after being awarded his Doctorate, he was invited to Trantor by Hari Seldon to join the psychohistory project. He met Seldon shortly after arrival on Trantor, but was already under surveillance by agents of the Committee of Public Safety. Seldon revealed to him that psychohistory had predicted the fall of the Imperium to be unavoidable, and that exile to the remote planet of Terminus was in fact Seldon's real goal. Gaal was arrested and interrogated.
After the exile, he carried the crisis tapes recorded by Hari Seldon to Terminus. He also oversaw the construction and installation of the Time Vault. Gaal Dornick became one of the key workers with Stettin Palver on Seldon's Plan, reporting directly to Seldon on its progress as they refined it. After Seldon's death, he moved to Terminus. Seldon's own version of the Prime Radiant was bequeathed to him and shipped after Seldon's death. Since no Prime Radiant appears later in the First Foundation, it is likely that Dornick did not stay permanently on Terminus.