Though they were wildly different shows, Smallville shared a surprising number of cast . Riding the wave of vampire hysteria in the late 2000s, The Vampire Diaries began airing in 2009 and ran for an impressive eight seasons, and even had two spin-offs in the form of The Originals and Legacies. The series was a blend of romance, horror, and fantasy, which opened the door for a host of unique storylines involving witchcraft, werewolves, and vampires. The show's roster of performers often included up-and-coming stars, and The Vampire Diaries was the launching pad for notable names like Ian Somerhalder and Nina Dobrev.
The Superman series Smallville, which debuted in 2001, also appealed to a teen audience, though its DC Comics background was quite distinct from the vampire romance of The Vampire Diaries. Even so, many of the best episodes of Smallville featured elements of fantasy and romance that catered to the Vampire Diaries faithful. Interestingly, the two series shared the same home network, The CW, and it wasn't unusual for actors to appear in many different projects for the station. Even though the two series only overlapped for two years on the air, notable names from the superhero program often found their way to Mystic Falls.
Cassidy Freeman - Sage/Tess Mercer
Cassidy Freeman has positioned herself as a TV mainstay in critically acclaimed shows like The Righteous Gemstones and Longmire, and her career saw her a frequent guest star on CW programming. Instantly recognizable to The Vampire Diaries fans as Sage from season 3, Freeman portrayed the ancient vampire as a cold and unfeeling monster toward humans, but a clever mentor to her fellow bloodsuckers. Sage taught Damon everything he knew about being a vampire, and many of the worst things Damon ever did on TVD were a result of her instruction. Even though she wasn't a villain, she embodied the complicated nature of TVD's vampire characters.
A few years before she entered the TVD universe as Sage, Freeman's turn as Tess Mercer had already shown off her skills at playing conflicted characters. Debuting in Smallville season 8, Mercer was Lex Luthor's younger sister, who was originally devoted to her brother but quickly turned on him when he betrayed her trust. She was essentially a villain like her brother, but she eventually had a change of heart regarding Clark Kent. Freeman sunk her teeth into the role with vigor and nailed the difficult task of making Mercer a likable character even after two seasons of being the main antagonist of the series.
Ian Somerhalder - Damon Salvatore/Adam Knight
Before becoming a fan favorite in his Damon and Elana-centric episodes of The Vampire Diaries, Ian Somerhalder had already accomplished a lot in his television career. As Damon Salvatore in all eight seasons of the show, he was more than a main character, serving as the dark heart of the series. Damon's dark side often emerged when romantic entanglements were concerned, and his education from his mentor, Sage, made him generally dismissive of human life. Somerhalder's naturally charming look was perfect for playing the eldest Salvatore brother, and both sides of Damon's personality were appealing in their own way.
Similar in tone, but not in execution, Somerhalder's character on Smallville was the young actor's first chance to show off his dark side. Adam Knight was a lackey for Lionel Luthor, who was granted metahuman abilities so that he could spy on Clark to learn his Superman secret. Knight's creepy obsession had none of the charms that Somerhalder would later show in Damon, and the character was downright villainous. Though not as complex as Damon would be, Somerhalder showed flashes of what he would bring to the table in The Vampire Diaries.
Benjamin Ayres - William Tanner/Jason Bartlett
Benjamin Ayres didn't have large roles in either of his CW appearances, but he nevertheless managed to make his mark with what he was given. Ayres appeared as William Tanner in the first three episodes of The Vampire Diaries, and the snide teacher reveled in picking on young Elena, much to the chagrin of Stefan. His three-episode stint ended when he was killed by Damon in what was far from one of the most heartbreaking deaths in The Vampire Diaries. Ayres's Smallville role didn't give him as much to do; he appeared in season 6 as Jason Bartlett, an advisor to Lex Luthor who was eventually killed by the phantom.
Sara Canning - Jenna Sommers/Kat
Despite being around the same age as her co-stars in The Vampire Diaries, Sara Canning stepped into the role of Jenna Sommers like a seasoned veteran. Jenna was Elena and Jeremy's aunt who took custody of her after the death of her parents and sacrificed her young adulthood to care for her niece and nephew. Jenna played a large part in the lives of Elena and Jeremy through the first two seasons of the show, and she became more sure of her guardian status. For her part, Canning deftly acted her way through Sommers' subtle emotional arc, and she was even one of The Vampire Diaries' short-lived vampires as well.
Acting alongside her fellow future The Vampire Diaries alumnus Cassidy Freeman, Canning appeared in season 8 of Smallville as Kat, the personal assistant to Tess Mercer. While her role was considerably smaller, only two episodes, she created a world for Kat that played out in little ways on screen. She was immediately seen to be a self-starter and even suggested having Clark Kent surveilled without any prompting from her boss. Unlike Jenna from The Vampire Diaries, Kat was as cold and calculating as the Luthor family that employed her.
Paul Wesley - Stefan Salvatore/Lucas Luthor
With his later turn as Captain James T. Kirk on Star Trek: Strange New Worlds, Paul Wesley once again found himself deeply embedded in a popular TV franchise. Before that, Wesley portrayed Stefan Salvatore in The Vampire Diaries and, along with his brother Damon, was one of the series' central protagonists. Stefan changed greatly after Vampire Diaries season 1, and his arc saw him struggle with his vampirism and the dark things he had to do. Unlike Damon, who enjoyed his evil side, Stefan spent all eight seasons grappling with it, and Wesley's performance perfectly carried the weight of Stefan's years.
Paul Wesley's early role in Smallville saw him play Lucas Luthor, brother to Lex, and this character was quite different from Stefan Salvatore. Appearing only in Smallville season 2, episode 15, "Prodigal," Lucas Luthor had the same drive to succeed as his brother Lex, but his incredibly volatile personality made him unstable. Not afraid to use violence to get his way, Lucas even got into an altercation with Clark Kent on the basketball court to prove how tough he was. Truly a one-off role, Wesley's Lucas Luthor was written off at the end of "Prodigal" and was never heard from again.
David Gallagher - Ray Sutton/Zan
Though every werewolf in The Vampire Diaries had some evil in them, the ill-fated Ray Sutton was actually more of a victim. Played by David Gallagher in the first two episodes of season 3, Ray was a werewolf who was tortured by Stefan and Klaus in order to reveal the location of his pack. To add insult to injury, Klaus then turned Ray into a hybrid, which eventually lead to his death at the hands of Stefan. With only a two-episode arc to work with, Gallagher inhabited the tragedy of his character, and Sutton was a reminder that being a member of the undead wasn't always glamorous.
By contrast, Gallagher's role as Zan in Smallville saw him as one-half of the bubbly, overambitious, and weird adaptation of the Wonder Twins who were part of the Teen Titans in season 9. Though it was only a few years before Gallagher would debut in The Vampire Diaries, his take on Zan highlighted the immaturity of the youthful wannabe hero, and that naive nature got him into trouble with his idol, Blur. Even if he only appeared in Smallville, season 9, episode 8, "Idol," Gallagher helped bring a piece of the DC Comics universe to life for the first time.
Sean Faris - Ben McKittrick/Byron Moore
With so much of The Vampire Diaries surrounding the undead characters, many of the humans became unwitting victims of the vampires' ancient schemes. Sean Faris entered the Vampire Diaries universe as one such character when he played Ben McKittrick in three episodes of season 1. Ben was a man adrift after graduating from high school, and the vampire Anna took advantage of his listlessness. Like how Anna was turned into a vampire by Katherine, Ben was turned by Anna so that he could spy for her. That disregard for human life resulted in Ben's death after he couldn't handle the euphoric early days of vampirism.
Ironically, Faris's guest role on Smallville was quite similar to his Vampire Diaries part, as he played Byron Moore, a teen who was given metahuman drugs by Metron Pharmaceuticals. Much like Ben, Byron was used by a higher power largely against his will, and Faris's natural performance in both shows really sold the out-of-control nature of his characters. Only appearing in Smallville, season 2, episode 5, "Nocturne," Faris was nevertheless one of the most memorable villains of the week.
Trent Ford - Trevor/Mikhail Mxyzptlk
Playing the role of Trevor in The Vampire Diaries, Trent Ford was given a character with a lot of emotional depth, even if he appeared briefly. Seen first in season 2, episode 8, "Rose," Trevor was a former love interest of Katherine's in the distant past but had been on the run from the Originals for centuries. He concocted the plan to kidnap Elena in order to buy his freedom from his pursuers, but Stefan put a stop to his machinations forever. Ford's performance brought out the desperation in the character, and it was abundantly clear that the centuries of running had not been kind to him.
Appearing in Smallville, season 4, episode 7, "Jinx," Ford inhabited a much more impish character in the form of exchange student Mikhail Mxyzptlk, an arrogant metahuman who could control people's actions with his mind. He attempted to use his powers to win a bet on the local high school football game, but Clark stopped him. Unlike the tired desperation of The Vampire Diaries' Trevor, Mxyzptlk allowed Ford's mischievous side to come out in one of the most comic-accurate villains in Smallville.
Allison Scagliotti - Georgie/Jayna
Rivaling even her undead counterparts in of complexity, Allison Scagliotti's role as Georgie Dowling in The Vampire Diaries season 8 was one of the most complex humans the show ever introduced. Guilt-ridden for the death of her friend, Georgie became an expert in Hell and was called upon by Alaric for her expertise. Despite the darkness that existed within her, Scagliotti's performance showed the fun-loving side of Georgie, and her eventual death was even sadder because she was literally dragged to Hell. Scagliotti appeared in Smallville, season 9, episode 8, "Idol," as Jayna, the naive other half of the Wonder Twins along with fellow Vampire Diaries actor David Gallagher.
Marci T. House - Mrs. Clarke/ER Nurse
Though The Vampire Diaries' pilot drew Twilight comparisons, it set the series off on the right foot with Marci T. House co-starring in one of Damon's first scenes in the show. Playing school Mrs. Clarke, House used every bit of what she was given when subtly shifting her performance after being compelled by Damon. A few years before her turn on The Vampire Diaries, House had a bit part in Smallville, season 7, episode 1, "Bizzaro," where she was an ER nurse who worked on Chloe after she overexerted herself when using her powers to save Lana.