The resulting ad -- celebrating iconoclasts from Gandhi to Einstein ("Here's to the crazy ones, the misfits, the rebels, the troublemakers, the round pegs in the square holes ...") -- was signature Clow. It tugged at the heart and purse strings simultaneously. Clow's "Think Different" campaign went on to help Apple sell out its first batch of iMacs -- and made an Apple the sidearm of choice for creative professionals.

But grammarians nationwide were enraged over the ads. "'Think Differently," teases Clow, 65, sitting in TBWA\Chiat\Day's playground warehouse in Playa del Rey, California, and resembling a surfing Santa (three boards are propped up in his office; a Ray-Ban tan line frames his eyes). "We had a lot of teachers telling us it was terrible." But for the college dropout who originated West Coast -- style advertising -- showing up for work for the past 45 years in shorts and flip-flops -- ignoring the rules is the very thing that has allowed him to push the boundaries for brands such as Adidas, Nike, Sony PlayStation, and more. "Advertising before Lee was different from advertising after Lee," says Crispin Porter + Bogusky's Alex Bogusky. "He didn't have so much respect for the form that he wasn't willing to mess with it." Mary Warlick, who runs the One Club, the arbiter of creative excellence in advertising, credits Clow with leading the industry's second creative revolution, elevating the humble slogan to become a species of entertainment in its own right. "He pushed advertising to an art form," she says.

Clow's next revolution is something he calls "media arts," a term that describes how brands can be made inseparable from culture. He believes every brand touch point needs to be treated as if it were an opportunity to seduce an audience -- like the Apple stores he helped conceive, or the new Gatorade bottles his agency recently designed. "You know all the posters that Toulouse-Lautrec did? Those were ads!" he says. "When advertising's done well, I think it can become part of our culture. When it's done badly, it becomes visual pollution."

In an industry that tends to spit out anyone with a speck of gray hair, the brain behind the Energizer Bunny, the Taco Bell Chihuahua, and Adidas's "Impossible Is Nothing" campaign continues to be one of the most creative forces in the game. Last year, as global director of media arts for TBWA\Worldwide, he helped the Omnicom-owned agency lure a phenomenal roster of new business, including Pepsi and the global Visa account. And while these days Clow considers his role more maestro than soloist ("I feel like I get to conduct this brilliant orchestra"), he still obsesses over the latest John Hodgman -- Justin Long "Get a Mac" spots for Apple, which are now conceived in a biometrically sealed fortress across the parking lot.

Clow says the intellectual pull that initially drew him to the business is the very thing that keeps him from walking away. "An art director is someone who loves ideas as the centerpiece of what you're creating," he says. But even for an anti -- Mad Man (he's been married to his wife, 15 years his senior, for 40 years; "he's never done a drug in his life," whispers a coworker), Clow still has the other part of his head to feed.

"Creative people are basically this 50-50 blend of ego and insecurity," he says. "From an ego standpoint, you think you're hot shit, but really, deep down, when you go to bed at night, you go, 'I don't know if I'm good enough. I'll try to make it better tomorrow.' " -- by Danielle Sacks