Giskard was a robot designed and built on Aurora by Han Fastolfe, and a lifelong companion of Fastolfe. As an unintended result of experiments in programming carried out on him by Fastolfe's student daughter Vasilia, Giskard was given the ability to read and influence minds of humans and robots. Although he used this ability according to the Laws of Robotics, this nevertheless included using it to prevent its discovery, and only Elijah Baley, during the investigation of R. Jander Panell's death, and Vasilia Aliena, at the height of the crisis between Aurora and Earth, deduced the extent of his powers.
Though he is a tin-like robot, he was the favorite robot of Fastolfe's estranged daughter. It was her experiment that gave R. Giskard his almost magical powers. It was Giskard's agreement with the views of Fastolfe on the future of the Spacers and of Earth people which led him to induce Panell into stasis when he discovered that Kelden Amadiro had been trying to extract information on humaniform robots from Panell for his own purposes, and to encourage the assignment of Baley to the subsequent investigation. His encounter with, and observations of, Baley convinced him that Fastolfe was right, and he continued to use his powers, when necessary, to encourage the mass emigration from Earth which Fastolfe wanted to see; Giskard traveled to Earth with him and was able to reprogram some of Earth's robots to influence the Earth's officials towards a more positive attitude to colonization.
After Fastolfe's death, ownership of Giskard and his long-time friend R. Daneel Olivaw transferred to Gladia, and with her they accompanied D.G. Baley via Solaria and Baleyworld to Earth, where Giskard could observe human beings en masse, and develop psychohistory and Zeroth Law of Robotics. While on Earth he prevented Amadiro from initiating his plan to destroy Earth but allowed Levular Mandamus to, determining that a long, slow death for the planet would be in the best interests of humanity by forcing them to expand into the galaxy.
He bestows this ability to Daneel, who in the Foundation series appears as Chetter Hummin, the journalist who manipulates Hari Seldon to create Psychohistory, and Eto Demerzel, the Emperor's Prime Minister.
After long and detailed discussions with Daneel, Giskard recognised the need for a Zeroth Law of Robotics as proposed by Daneel as an answer to what both had come to see as the incompleteness of the existing Laws of Robotics. Giskard was less able to cope with the abstract concepts that the Zeroth Law introduced, and went into stasis as a result of the lingering uncertainty of his decision to allow Earth to die, coming as it had at the end of a protracted series of difficult crises. Before freezing, he programmed Daneel with his telepathic powers.
In Foundation and Chaos, the second volume of the Second foundation trilogy set 20,000 years after these events, it is revealed that Giskard's head was preserved by fellow robots during these millennia and that its memory can still be accessed, although mental processing has ceased.