Federation cultural observer and noted professor of history. As a historian, Gill emphasized the study of causes and motivations, rather than dates and events. He was an instructor at Starfleet Academy whose students included future Enterprise Captain James T. Kirk.

In the late 2260s, Gill was stationed on planet Ekos, where he conducted a disastrous cultural experiment in which he violated the Prime Directive in an effort to give the planet a more efficient form of government, patterned after Earth's Nazi Germany, but based on more compassionate principles. The experiment failed terribly when those near him were corrupted by power and sought to create racial hatred against the neighboring planet, Zeon. In 2268, Deputy Fuhrer Melakon murdered Gill when he sought to discredit the program of genocide launched against Zeon.