Each of the main characters in Smallville discovered the truth about Clark Kent (Tom Welling) being Superman at very different times in the series. Like most superhero stories, one of the most important elements of Smallville was Clark’s secret identity. Since the pilot episode, Clark tried to protect the secret of his powers and his Kryptonian heritage from the people around him, but there were times when Clark either failed to hide the truth or was compelled to come clean.
Throughout most of Smallville, Clark Kent found himself in positions where he had to lie and keep secrets from the people closest to him. Despite his best efforts, however, the truth regarding his secret identity was discovered by various main characters. During Smallville‘s ten-season run, Clark met a number of people he was able to be honest with. With some, Clark came clean willingly, while others had to find out the truth on their own.
Pete Ross (Season 2, Episode 3)
In season 1, the only people Clark could talk to about his powers were his parents, Jonathan (John Schneider) and Martha (Annette O’Toole). That changed in Smallville season 2 when Clark’s best friend, Pete Ross (Sam Jones III), found Clark’s spaceship after it got swept up in the tornado from the season 1 finale.
Pete wanted to tell people about the ship, forcing Clark to come up with excuses to stop him. When Clark was blamed for the ship’s sudden disappearance, Clark told Pete his secret, knowing that it was the only way to preserve their friendship. Pete learned the truth in season 2, episode 3, “Duplicity.” Pete helped Clark keep his secret in seasons 2 and 3, but the burden it presented eventually got the best of him. To escape from it, Pete leaves the series in the penultimate episode of season 3.
Chloe Sullivan (Season 4, Episode 12 & Season 5, Episode 1)
In the season 4 episode “Pariah,” Clark’s girlfriend Alicia (Sarah Carter) became determined to leak his secret to the world, so she tricked Clark into using his powers in front of Chloe Sullivan (Allison Mack). Chloe watched in shock as Clark caught a car with his bare hands.
Hoping he would tell her about his abilities on his own, Chloe said nothing and assumed that Clark was meteor-infected. After unintentionally following Clark to the Fortress of Solitude, Chloe knew that there was more to his secret. After saving Chloe from freezing to death, Clark finally tells her everything in the season 5 premiere “Arrival.”
Lionel Luthor (Season 5, Episode 15)
After interacting with one of the Kryptonian Stones of Power, Lionel becomes a vessel of Jor-El (voiced by Terence Stamp). Through the connection that was established by the Stone, Jor-El was able to take control of Lionel and use him to resurrect Clark when he was killed in Smallville season 5, though Jonathan Kent would die in exchange later in the season.
It was revealed that when Jor-El inhabited Lionel’s body, he left behind some of his Kryptonian knowledge (including the truth about Clark’s identity) in Lionel’s mind. The audience learns for sure that Lionel knows the truth about Clark in the episode “Cyborg.” Later, Lionel confessed to Clark that he knew he was Kal-El.
Oliver Queen (Season 6, Episode 4)
Just after his introduction to the series, Oliver Queen (Justin Hartley) was breaking into a museum as the Smallville version of Green Arrow when he was intercepted by Clark. Oliver, who witnessed Clark’s powers firsthand, tried to convince him to use his abilities to benefit the world, rather than just his Smallville friends.
Oliver became the first (and only) major character to figure out Clark’s secret within one episode of meeting him. In fact, both Oliver and Clark learned about one another’s secret identities in “Arrow,” and protected one another’s secret identities from then on.
Lana Lang (Season 6, Episode 16)
Clark spent six seasons agonizing over what to do about Lana Lang (Kristin Kreuk) and his secret. Various obstacles prevented him from telling her, ranging from his own fear that she would blame him for the death of her parents, to his concern that knowing the truth would be too much of a burden for her to bear.
In the season 5 episode “Reckoning,” Clark finally told her and proposed. Unfortunately, this decision was undone when Clark had to turn back time to stop her from dying. As a result, Clark kept his secret hidden from her for another year.
In season 6, Lana, who knew Clark was hiding something ever since she saw him save her from the tornado, decided that if he wouldn’t tell her the truth, she would find it on her own. After setting a trap for Clark on the day of her wedding to Lex (Michael Rosenbaum), she witnesses him using his powers in the episode “Promise.”
She thought this was the whole story, until Clark told her that he was from another planet in the season 6 finale. Clark admitted to Lana in season 7 that he had no idea why he was ever worried that she wouldn’t understand.
Lex Luthor (Season 7, Episode 20)
After becoming a full-fledged villain in season 7, Lex murdered his father and plunged himself deeper into the mystery of the Traveler, the name given to the alien who came to Earth in the meteor shower. After finding the location of the Fortress of Solitude and uncovering a way to gain control over the Traveler, Lex asked Brainiac (in the guise of Laura Vandervoort’s Supergirl) who the Traveler was.
Brainiac responded, “Don’t you already know?” implying that Lex had the clues for Clark’s identity. Lex apparently put the pieces together, and was not surprised when Clark confronted him in the Fortress for their final battle in the finale, “Arctic.” Lex would eventually forget the truth about Clark’s identity, though, when he was infected with a toxin later.
Davis Bloome (Season 8, Episode 18)
Davis Bloome (Sam Witwer), the human form of Doomsday, suffered from blackouts and was unaware for a long time that he was a Kryptonian monster created to kill Clark. Tess Mercer (Cassidy Freeman), believing that Clark had to kill Doomsday to become the hero he was fated to be, told Davis about his destiny and his connection to Clark toward the end of season 8. Davis learned the truth about Clark in the episode “Eternal.”
Tess Mercer (Season 8, Episode 21)
Tess Mercer knew there was something up with Clark when she came to Smallville to replace Lex in season 8. Lex’s obsession with Clark was enough to give her a few clues. She even orchestrated a plane crash to force Clark into exposing his abilities, but her plan didn’t work.
Toward the end of season 8 in the episode “Injustice,” she uncovered Lionel’s journal and found out everything she needed to know about Clark. When she told Clark that she knew the truth, he didn’t trust her at first; however, in time, Clark gained enough confidence in Tess to invite her to join Smallville’s Justice League.
Jimmy Olsen (Season 8, Episode 22)
Jimmy Olsen (Aaron Ashmore) started to suspect that Clark was the Red-Blue Blur (Clark’s vigilante identity for season 8), when his research into the hero’s rescues pointed him directly at Clark. Clark temporarily allayed Jimmy’s suspicions by arranging for Oliver to pose as the Red-Blue Blur in “Identity.”
However, the truth was exposed once Jimmy saw him heal from a wound in the season 8 finale “Doomsday.” Unfortunately, though, Jimmy wasn’t in on Clark’s secret for long. Jimmy was killed by Davis in the same episode, leading Clark to renounce his humanity.
Lois Lane (Season 9, Episode 21)
From Smallville seasons 2 to season 6, Clark had to fend off questions from a suspicious Lana, but he didn’t have the same problem with Lois Lane (Erica Durance), who remained oblivious to Clark’s secret identity for most of the series. While Lois did learn the truth in the season 8 episode “Infamous,” time was reversed and undid that reveal.
Things took a turn in the Smallville season 9 finale “Salvation,” when Clark (as the Blur) saved Lois from Zod (Callum Blue) and kissed her. After he left, Lois was able to tell from the kiss that Clark was the Blur all along. However, she didn’t tell Clark about this, and just as Chloe did in season 4, she waited for Clark to tell her himself. In the season 10 episode “Isis,” Clark confessed to Lois that he was the Blur, and was surprised to find out that she already knew.