R. Giskard Reventlov is a pre-humaniform 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 Fastolfe, Giskard was given the ability to read and influence minds of humans and robots.
With R. Daneel Olivaw he created the "Zeroth Law of Robotics," an extension/modification of the Three Laws of Robotics, which helped him prevent Kelden Amadiro's destruction of the Earth—though the same law led him to allow a gradual destruction of the Earth through radioactive increases, which would encourage the colonization of the Galaxy. Just before he shuts down, he transfers his telepathic abilities to R. Daneel Olivaw.
Read more about this topic: List Of Isaac Asimov's Robot Series Characters