Heroes

Harry Potter: Born July 31, 1980
Buffy Summers: Born January 19th, 1981

By straight Strauss & Howe numbering, both are Nomads. However, they are both Capital-H Heroes, taking on important roles in the Crisis, fighting their respective Big Bads, succeeding through teamwork and sacrifice - indeed, both make the ultimate sacrifice to save their friends and the world. (In Buffy's case, more than once.)

They also distinguish themselves as leaders, although evidently because they are forced into it by circumstances more than due to a specific need or aim.

Heroes show up when they are needed, and expected. Buffy and Harry showed up in the 1990s, just as an actual Hero generation was coming of age. It all goes together, even if it doesn't always line up exactly as expected.