Leonard Boyarsky is one of the original masterminds behind the Fallout world and the first Fallout game.
After receiving a Bachelor of Fine Arts degree from the Art Center College of Design, Boyarsky began work as a freelance artist in 1992. Some time later he was hired as a cleanup artist at Interplay, later becoming the lead artist on Stonekeep. This eventually lead to his becoming the lead artist/art director on the GURPS project that later became Fallout. Aside from guiding the art on the project, together with Jason Anderson, Tim Cain, Scott Campbell and Chris Taylor, he oversaw the direction and feel of the game. He left Interplay after helping to complete the initial design for Fallout 2 and, together with Cain and Anderson, was a founder of Troika Games.
I did approach Bethesda about us working with them on Fallout, but they were uninterested. Instead of flaming them for this however, think about it from their point of view: who among us would want to pay a huge amount of money for a license and then turn it over to someone else? I'm assuming they paid the cash because they wanted to make a Fallout game, end of story. - RPG Codex forum
Leonard was the person responsible for Fallout's famous ending involving the Vault Dweller's exile into the desert.
He came up with the alternate flag of the United States with 14 stars and the initial idea for 13 super-states, but the idea was further developed only by Joshua Sawyer during the development of Van Buren.