Buffy the Vampire Slayer followed teenager Buffy Summers as she trained to become the Vampire Slayer, battling against supernatural threats during the show's seven-season run. Buffy the Vampire Slayer aired from 1997 to 2003 and stands proudly as one of the best-known fantasy television shows of all time. The show focused on Buffy and her friends during their high school years and also featured an array of supernatural allies and foes.

In the show's initial season, Buffy starts her sophomore year at Sunnydale High, having just left Los Angeles following an incident with a group of vampires. Shows with teenage protagonists tend to cast actors who are older than the characters, as filming with underage actors requires them to be tutored, which can slow down the production process. The Buffy the Vampire Slayer varied in age compared to their characters, with some age differences spanning centuries.

9 Seth Green As Oz

Seth Green Was 23 When He Played 17-Year-Old Oz

Family Guy and Austin Powers star Seth Green was five years older than his Buffy The Vampire Slayer character, being in his early 20s when playing the teenage werewolf Oz. Seth Green was introduced as Oz in the season 2, episdoe 4, "Inca Mummy Girl", and eventually became the boyfriend of Willow, despite him being a werewolf.

While this seems like a large age gap, it was smaller than many of the other Buffy the Vampire Slayer cast

Green was 23 when he was cast as the high school junior, only five years older than Oz (while this seems like a large age gap, it was smaller than many of the other Buffy the Vampire Slayer cast ). Oz was one of the show's main characters until season 4, when he broke up with Willow and traveled to Tibet to focus on controlling his werewolf form. Oz reappeared briefly toward the end of Buffy the Vampire Slayer season 4 looking to reconcile with Willow, but by then she had already moved on with Tara, so he left.

8 Anthony Stewart Head As Rupert Giles

Anthony Steward Head Was 43, The Same Age As His Buffy Character

Buffy's voice of reason, librarian Rupert Giles was played by Anthony Stewart Head, the only actor in Buffy the Vampire Slayer to be cast at the same age as their character, with both being 43 years old. More than just a mentor, Giles was often a father figure to Buffy, guiding her through her responsibilities as the Slayer, and also helping rehabilitate Willow after she nearly destroyed the world.

Giles started as Buffy's "Watcher" (an official role for the guide of the current Slayer), and despite being replaced at various points throughout the series by the Watchers Council, he remained her steadfast ally. Though he did move back to England, both because Buffy had died and later, when she was back, so she could learn independence, GIles was always there for her. After the show ended, there were rumors of a spin-off focusing on Giles, but it was never made. By the time Buffy the Vampire Slayer concluded, Anthony Stewart Head had just entered his 50s.

7 Charisma Carpenter As Cordelia Chase

Charisma Carpenter Was 27 When She Played 16-Year-Old Cordelia Chase

Of all the human characters in Buffy the Vampire Slayer, Charisma Carpenter had the largest age gap between actor and the Sunnydale High student she portrayed. Carpenter was 11 years older than popular girl Cordelia Chase, and while it wasn't really noticable when the show first aired (and it was common practice to cast adults as teenagers) it's rather obvious when rewatching the earlier seasons of Buffy the Vampire Slayer today.

Since Cordelia was an adult in Angel, the age gap between Charisma Carpenter and her character was much less jarring.

Cordelia was initially hated by Willow for her standoffish attitude, but over her time on the show, grew closer to her and Buffy. The character then left Buffy the Vampire Slayer, taking a main role in Angel, before being killed off in the one-hundredth episode, entitled "You're Welcome," which aired in 2004. However, since Cordelia was an adult in Angel, the age gap between Charisma Carpenter and her character was much less jarring.

6 David Boreanaz As Angel

David Boreanaz Was 28 When He Played The 270-Year-Old Vampire Angel

Angel, Buffy's vampire friend-turned-lover, was played by David Boreanaz, who was a whole 242 years younger than the character. Technically, Angel had the largest age difference between actor and character, both human and supernatural. Angel appeared in the show until its third season, leaving Buffy behind after realizing their relationship had reached its limitations.

28-year-old actor Boreanaz was also slightly older than his character's human age.

However, while Angel was 270 by the time he met Buffy, he was turned into a vampire at age 24. While this creates a few issues for Buffy and Angel's already problematic relationship, it does mean that 28-year-old actor Boreanaz was also slightly older than his character's human age. Following his departure, Boreanaz then starred in the Angel spin-off, which ran for five seasons from 1999 to 2004, and saw several of the original cast from Buffy the Vampire Slayer reprise their roles for guest appearances.

5 James Marsters As Spike

James Marsters Was 35 When He Played The 117-Year-Old Vampire Spike

Spike, the widely-feared vampire responsible for the deaths of two previous Slayers, was played by actor James Marsters, and was introduced in season 2, episode 3, "School Hard". Marsters was 35 years old when he was cast as Spike, making him 82 years younger than the supernatural threat. Spike's age when he was turned into a vampire in 1880 was never fully disclosed, though he was an adult.

It's likely that Spike was in his mid-20s when he was sired though, meaning that James Marsters sticks to the Buffy the Vampire Slayer trend of casting actors older than their characters. Despite Spike being a complex anti-hero, he eventually became an ally to Buffy, and over time began to fall in love with the Slayer. Spike was killed off in the final season, before being resurrected after the events of the show. He then ed the cast of Angel, which saw the character revert to his old ways.

4 Nicholas Brendon As Xander Harris

Nicholas Brendon Was 26 When He Played The 16-Year-Old Xander Harris

The character of Xander was introduced as one of Buffy's best friends in the first season and appeared in all but one episode of Buffy the Vampire Slayer. Xander was an awkward, dorky student who often got bullied by his peers at Sunnydale High — and, like many of the young human characters in the show, was played by an actor who was several years his senior. Xander was portrayed by 26-year-old Nicholas Brendan, who was a whole decade older than his character when Buffy the Vampire Slayer debuted.

Next to Charisma Carpenter as Cordelia, Nicholas Brenden had the widest age gap between himself and his character, though this didn't present many issues as the show progressed. Xander remained a main character across all seven seasons, and when Buffy the Vampire Slayer ended in 2003, 33-year-old Nicholas Brendon was playing a 23-year-old Xander.

3 Alyson Hannigan As Willow Rosenberg

Alyson Hannigan Was 23 When She Played The 15-Year-Old Willow Rosenberg

Alyson Hannigan, who went on to play the character of Michelle in American Pie and Lily in How I Met Your Mother, was cast as Willow at the age of 23. Willow was among the youngest characters in Buffy the Vampire Slayer, and at age 15 at the start of season 1, actress Alyson Hannigan was eight years older than her character.

Willow was also a part of one of the first lesbian relationships ever shown on U.S. television.

Willow started Buffy the Vampire Slayer as a shy nerd, and ended as a strong and confident witch. There was even a brief stint in Buffy the Vampire Slayer season 6 that saw Willow as a villain, which was foreshadowed four years previously. Willow was also a part of one of the first lesbian relationships ever shown on U.S. television and is the only other star besides Sarah Michelle Gellar to appear in every single episode of Buffy the Vampire Slayer. Hannigan also guest-starred in three episodes of Angel during its five-season run.

2 Sarah Michelle Gellar As Buffy Summers

Sarah Michelle Gellar Was 19 When She Played The 16-Year-Old Buffy Summers

Buffy Summers was played by Sarah Michelle Gellar, who was only 19 when Buffy the Vampire Slayer first aired in 1997. However, she also had the smallest age gap between actor and character among the Buffy the Vampire Slayer cast. Buffy Summers was 16 when the show began, meaning the age gap between her and Sarah Michelle Gellar was only three years.

Gellar played the vampire slayer for all seven seasons before the show came to an end in 2003. The breakthrough role for Gellar helped launch her career into superstardom, making her one of the most notable and well-loved female leads in TV history. Gellar is also one of only two actresses to appear in all 144 episodes of Buffy the Vampire Slayer and also appeared briefly in the Angel spin-off.

1 Older Actors Playing Teens Is A Trope Of The Era

The '90s And 2000s Saw Many Young Stars In Their 20s Playing Teenagers

Seeing some of the Buffy the Vampire Slayer cast's ages compared to the characters they are meant to be playing can be surprising, but adults playing teenagers was not uncommon in movies and television from the 1990s and 2000s. This was an ongoing trend of the era which can give new context to some of the classic and fan-favorite movies and shows to come out of this time in Hollywood.

As a sign of the trend, many of the Buffy the Vampire Slayer cast played teens in other projects during this time, such as Sarah Michelle Gellar in I Know What You Did Last Summer, Alyson Hannigan in American Pie, and Seth Green in Can't Hardly Wait. Other shows at the time featured similar age gaps with 29-year-old Gabrielle Carteris playing 16-year-old Andrea Zuckerman in Beverly Hills 90210. Meredith Monroe was also 29 years old when she started playing teen character Andie Mhee on Dawson's Creek.

Some of the best movies from the era also featured similar age gaps. While Alicia Silverstone was 18 years old and Kirsten Dunst was 17 years old in Clueless (1995) and Bring it On (2000) respectively, their costars were older. Stacy Dash was 29 when she played Cher's best friend Dionne in Clueless, while Gabrielle Union was 31 years old when she played rival cheerleader Isis in Bring It On. Rachel McAdams was an up-and-coming actor when she scored the role of Regina George in 2004's Mean Girls, but she was still 24 when playing the teen character.

While these casting choices can seem odd, it is worth noting that in Buffy the Vampire Slayer and many of these teen movies and shows, the actors embodied their characters, and created icons that have been celebrated for generations.