(FORTUNE Magazine) – Power isn't a word you'll hear much around Wal-Mart. Huge concentrations of it scare people, and any superpower seen to be throwing its weight around is apt to lose some of it. Lee Scott (above right) seems to understand this. But despite his studiously low profile, the CEO of America's biggest company (No. 1 on the FORTUNE 500 list, with $247 billion in sales and nearly 1.4 million employees) can't help but be a powerful man. True, he's more the channeler of Wal-Mart's power than its source. It was founder Sam Walton (above left) and successor David Glass (center)--the other two-thirds of retailing's holy trinity--who built the machine and the culture underlying it. But if you're at the controls of the biggest starship in the galaxy, you are, by definition, a Master of the Universe. --Jerry Useem