Some coworkers bond over football, or horrible bosses. My colleagues and I spent most of our recent holiday party nerding out over an 18-year-old vampire television series.

That would be, of course, Buffy the Vampire Slayer, the series that put director Joss Whedon on the map and that quickly became a how-to-do-life manual for many women, of many generations. That was apparent when the topic came up during a holiday-party discussion with my colleagues, Inc. editor-at-large Leigh Buchanan and Inc. social media editor Stephanie Meyers.

Both of them are even more fervent about the show than I am; as Leigh writes today, “The only motivation you need to watch Buffy is curiosity about how great leaders are forged. Women especially. If you have daughters, watch it with them.”

Buffy was the original superhero, one who’s informed so many of the interesting and complicated--not just “strong”--female role models of TV today. I have my issues with Whedon, his feminism, and parts of how it manifests in Buffy (just tally up the death counts of male versus female characters in that universe), but I’ll always give the man credit for helping to start a revolution in how women get to be portrayed on TV and in pop culture.

The women of Buffy get to make mistakes, and to recover from them, and to change as they grow up. They get to be leaders and role models of many different styles, without arguing that one is necessarily the best. (Contrast Buffy’s stake-first-ask-questions-later willingness to act with Cordelia’s socially-savvy politicking or Willow’s deliberate researching and reasoning.)

Two decades later, it’s funny--frustrating, but funny--to see the persistent dearth of female superheroes at the movie theater, because so many of them now populate the smaller screen. There are the overt comic-book characters, like the new Agent Carter. There is the incredibly grey-shaded Olivia Pope, fearless leader of Scandal’s entertainingly horrible political gladiators. There’s Homeland’s Carrie Mathison, who makes terrible decisions and yet survives; there’s The Good Wife’s Alicia Florrick, who started from powerlessness and who has spent six years learning how to revel in power and ambition; there’s the defiantly unlikeable Hannah and her friends on Girls, who may not be superheroes but who get to make as many mistakes as mere mortals. On the other end of the spectrum, there’s my recent favorite, Phryne Fisher of Miss Fisher’s Murder Mysteries, who gets to be a 1920’s Australian flapper version of James Bond. All of them owe a debt to Buffy, and to Whedon.

Monday, January 19, is Buffy Summers’s 34th birthday. To help her celebrate (with hopefully fewer crises than normal), Leigh reflects on what Buffy taught her about authority, analysis and sacrifice. Stephanie, meanwhile, points out that the most productive characters on Buffy were often its supervillains: “You don’t get to be a leader of demons without some serious entrepreneurial chops,” she writes, compiling a list of practical takeaways from the show’s Big Bads.