John Hill was a Manticoran citizen, a computer specialist, and diplomat.
He was a member of the delegation that was sent to Masada in 1892 PD aboard the light cruiser HMS Intransigent. He was very knowledgeable about the Masadans, including being familiar with their religious rituals and dietary restrictions. Crown Prince Michael, serving as a midshipman aboard the Intransigent at the time, was pretty sure Hill was in fact a spy, but also considered him to be the most competent member of the delegation. (HHA4.1: PL)