Gaal Dornick is a fictional character in Isaac Asimov's Foundation Series. He is the first character mentioned in the Foundation series, appearing in the first chapter of Foundation, describing his meeting with Hari Seldon. He became Seldon's biographer. He makes appearances in several other stories of the Foundation series, including Foundation's Triumph.
Gaal Dornick is a character in Part I of Foundation. He is a young mathematician, newly awarded his Doctorate, and originates from Synnax. He has been invited to Trantor by Hari Seldon to join the psychohistory project. He meets Seldon shortly after arrival on Trantor, but is already under surveillance by agents of the Committee of Public Safety.
Seldon reveals to him that psychohistory has predicted the fall of the Imperium to be unavoidable, and that exile to the remote planet of Terminus is in fact Seldon's real goal. Gaal is arrested, interrogated and eventually moves to Terminus to continue Seldons legacy.
Further details of Gaal's life are given in Forward the Foundation. After the exile, he carried the crises tapes recorded by Hari Seldon there. 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. Wanda Seldon had Hugo's Prime Radiant.
Since Bor Alurin is stated to be the only social scientist present in the First Foundation, and the Prime Radiant appears later in possession of the Second Foundation, it's likely that he didn't stay permanently in Terminus.
Gaal Dornick, using non-mathematical concepts, defined psychohistory to be
- ...that branch of mathematics which deals with the reactions of human conglomerates to fixed social and economic stimuli.