Fans of spawned a spin-off, Angel, and a Buffyverse canon that includes video games, novels, and comics.
The series features Buffy Summers, played by Angel. Buffy's inner circle, the only ones who know her true identity, became known as the "Scooby Gang." Over time, the group fluctuates in numbers, but additional characters included Cordelia Chase, Tara Maclay, Anya, Riley Finn, Jenny Calendar, Dawn, Oz, and Spike.
During season 4, the show introduces the first Slayer, Sineya. Her origin story is explained in greater depth during season 7. Using Shadow Casters, Buffy travels through a portal and encounters The Shadowmen. They are the ones who kidnapped Sineya, chained her to the earth, and imbued her with the powers of a demon. Buffy accuses the Shadowmen of using Sineya to kill for them because they were too weak. According to CBR, Whedon has said his mission statement for Buffy was always "the joy of female power: having it, using it, sharing it." In an article written for The Guardian by Anthony Stewart Head (Rupert Giles), he wrote, "Joss Whedon's original concept was to take the girl in the horror movies who falls over, twists her ankle – the victim – and make her the hero. It's clearly a feminist parable." In 2006, Whedon won an Equality Now award; during his acceptance speech, he stated that his goal with Buffy was to create a feminist icon. He also wanted to surround her with male characters who were attracted to her because of it.
When battling The First, Buffy builds an army of Slayers who haven't yet been called, so they lack the typical Slayer strength. The Shadowmen created a line of succession that ensured only a single Chosen female would be "active" at any given moment. However, Buffy's season 1 death created multiple Slayers existing at once. Buffy eventually shatters that legacy by sharing her Slayer strength with the Potentials in season 7. She's no weaker as a result, and it's a testament to what women can accomplish when they work collectively toward a common goal.
The closest thing the Buffyverse has to a male Slayer is Billy Lane. He makes his debut in Billy the Vampire Slayer, Part One, which is the fourteenth issue of the Buffy the Vampire Slayer Season Nine comic book series. Billy doesn't have the speed or strength of a Slayer, but according to Giles, in New Rules, Part 2—the second issue of the Buffy the Vampire Slayer Season 10 comics—"the essence of the Slayers has clearly accepted him as an ally." If Buffy the Vampire Slayer introduced one into the canon, it would diminish the legacy of Whedon's groundbreaking show.