Who has influenced economics and the study and understanding of it? Someone who I can write an essay about.?

My favorites are John Nash and Antoine Augustin Cournot of Cournot-Nash Equilibrium. Their studies were on game theory. And of course there is Adam Smith the famous classical economist.

You can write about John Maynard Keynes(fiscal policy, aggregate demand, natural rate of unemployment; basically set-up new age economics), Adam Smith (considered foundation of modern economics), Karl Marx(anti-capitalist), Milton Friedman(free markets), Malthus or Ricardo, the Institutionalists

Keynes is pretty relevant now, since there has been a revival of his theories. He definitely influenced economics.

Someone more modern might be Galbraith. He writes very well and his books are quite accessible.