PARIS — At the tail end of Paris Fashion Week, at a party whose threshold was near impossible to breach, Rick Owens was chatting up Kris Van Assche, the Dior Homme designer, not far from Emmanuelle Alt, the editor of Paris Vogue. Chloë Sevigny was holding court in one corner.

The evening’s host, however, was most excited by the presence of teenage skateboarders in sweatsuit finery. Inside they mixed with fashion editors, while outside many more waited on quiet rue Barbette, desperate to get in.

Supreme, the New York skate line and 22-year-young beacon of cool, had arrived.

Its impresario, James Jebbia, 52, is not generally given to discussing the phenomenon he has presided over for two decades. “The less known the better,” he said in a rare interview. He is its founder and owner but not its designer, and prefers not to delve too deeply into the specifics of who is. The star of Supreme is Supreme.

“Ralph Lauren has Ralph Lauren, Tommy Hilfiger has Tommy Hilfiger,” Angelo Baque, Supreme’s brand director, explained. “We like for Supreme to be at the forefront when you think of Supreme. That’s the key, at least for me, for the brand to stay ageless and timeless.”