Multiple factors led to Lex Luthor (Michael Rosenbaum) becoming a villain in Smallville. Smallville was an origin story for more than just Tom Welling’s Clark Kent. The Superman prequel series also explored how Lex Luthor evolved into the Man of Steel’s greatest enemy.

In this new take on Superman, Clark and Lex shared a strong friendship during the former’s high school years. After saving Lex’s life, Clark earned Lex’s loyalty and undying gratitude. Lex, who came to genuinely care for Clark, spent much time trying to gain favor with Clark’s parents and helping Clark win over Lana (Kristin Kreuk) in season 1. Though their bond faced numerous tests, it survived the first four seasons of the series. Like Lana, Chloe (Allison Mack), and Pete (Sam Jones III), Lex came to be someone Clark could count on when he needed help. Lex was always among the first to give aid to Clark or his family; however, Clark never did bring Lex into his confidence in regards to his Kryptonian heritage and powers.

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Clark and Lex’s friendship ended for good at the beginning of season 5, as Lex had drifted further and further down a dark path. During seasons 5, 6, and 7, Lex served as a principal antagonist for Clark, with his story culminating in the discovery of Clark’s secret at the end of season 7. Though Clark was far from becoming Superman, Lex was already a villain at this point. Years after his death in season 8, Lex was revived in the season 10 finale, where he completed his transformation into his comic book counterpart by killing Tess and losing his memories of Clark. Here’s every reason that Lex turned evil in Smallville.

Lex’s Relationship With Lionel Luthor

Many of the issues that Lex had in Smallville were related to his relationship with his father (or lack thereof). Lionel (John Glover), who was evil in his own right, kept his son at arms-length and raised him to have values that matched his own. Lex was taught what it meant to be a Luthor, which involved seizing power, becoming strong, and toppling those ahead of him. Unlike Clark’s parents, Lionel never tried to instill goodness in his son. What further troubled Lex throughout his life was the callousness of his father. Lex admitted in a season 3 episode that what he really wanted from Lionel was his love, but he understood that this was something that he could never have. For years, Lex was embittered by Lionel’s treatment of him. By the time Lionel realized the mistakes he made with Lex and tried to make up for what he did, it was already too late. Lex resolved his beef with Lionel in season 7 by pushing him out of a window, where he fell to his death.

Helen’s Betrayal

Lex found love in Smallville season 2 when he met Dr. Helen Bryce (Emmanuelle Vaugier). In trying to maintain a romantic relationship with her, Lex had to overcome his trust issues. Lex struggled to open his heart to Helen and eventually was able to commit himself fully to their relationship. After their wedding, an attempt by Helen to kill Lex left him stranded on a deserted island for months, where he suffered a mental breakdown. After returning and coming to the shocking realization that Helen tried to kill him, Lex got revenge on her. Helen’s betrayal hurt Lex, and pushed him one step closer to becoming a villain. Helen’s murder plot was one of many betrayals that hardened Lex’s heart.

Clark Refused To Trust Lex With His Secret

Smallville Lex Luthor and Clark Kent outfits

Lex viewed Clark as his “brother” and was constantly disappointed whenever Clark would shy away from trusting him with his secret. Lex long believed that Clark was hiding something from him, but could never be sure what it was. And of course, he was right. Regardless of how many chances Lex gave Clark in Smallville to come clean, Clark was never willing to share his secrets with him. It bothered him that not only did Clark fail to trust him, but he also lied to him. Lex had a high opinion of him and couldn’t understand why Clark never confided in him. Clark’s refusal to trust him completely often made him feel like Clark didn’t value their friendship in the same way. Needing his curiosity to be sated, Lex took matters into his own hands in order to get the answers he needed. The underhanded actions he took to get Clark’s secret were some of the first dubious deeds he committed in Smallville.

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Clark Ended His Friendship With Lex

Clark Kent confronts Lex Luthor over the Cyborg experiments in Smallville

Clark added his name to the list of people Lex felt had betrayed him when he told him that they weren’t friends anymore in season 5. Lex kidnapping Clark’s parents and Lana in order to force him into revealing his powers crossed a line, but Lex saw it a different way. He felt that it was Clark’s own secrecy that brought them to this. Clark ending their friendship only made things worse, and resulted in Lex feeling even more isolated. Clark himself mused in a season 6 episode that his decision to give up on Lex may have been what caused him to turn away from being good.

Lex Was Jealous of Clark

Tom Welling as Clark Kent and Kristin Kreuk as Lana Lang in Smallville

Part of what motivated Lex’s villainous and deceitful acts in seasons 5 and 6 was his jealousy of Clark. Lex manipulated Lana into entering a relationship with him, and also managed to trick her into accepting his marriage proposal by making her think she was pregnant. Under the influence of red Kryptonite, Clark called Lex out and accused him of only wanting Lana because he desperately desired to have what belonged to Clark. Whether Lex truly loved Lana or not, it’s true that Lex was deeply envious of the life Clark had throughout Smallville. Though Lex did want Clark to be with Lana in season 1, he hated seeing them together in season 5 and resorted to new lows to keep them apart. This included hiring a woman to hypnotize and seduce Clark right in front of Lana.

Lex’s Pursuit of Power & Knowledge

Lex Luthor has a vision of his future in Smallville, he has a white suit on, which is sprinkled with blood.

Arguably Lex’s greatest weakness in Smallville was his relentless pursuit of power and knowledge. Being Lionel Luthor’s son, it’s not a surprise that Lex had an obsession with becoming more powerful and gaining the answers to certain mysteries. The two Luthors were determined to unearth secrets related to Clark and the Kawatche caves, and both were willing to do whatever it took to accomplish this. Lex’s curiosity led him into making all sorts of morally questionable decisions. He was so interested in Kryptonite and its effects on people that he created the 33.1 facility to perform illegal experiments on meteor-infected humans. He also developed a desire to turn these people into weapons. In season 5’s “Lexmas,” which was a reversal of It’s A Wonderful Life, Lex experienced a dream where he had a family with Lana after giving up all his power. When Lana died as a consequence of Lex not having enough money or resources to save her, he decided that power was the key to his happiness. After waking up from the dream, Lex became more unscrupulous than ever, which was indicated by his willingness to ruin Jonathan Kent’s good name to win the Senate race.

Lex Was Split Into Good & Evil By Black Kryptonite

Lex Luthor Smallville

Some fans have theorized that what really made Lex into a villain on Smallville was the season 4 episode, “Onyx.” In this episode, Lex was split into good and evil halves by a piece of black Kryptonite. The evil Lex represented what he would eventually become, which was reflected by the line, “I am the villain of the story.” Clark managed to have the two merged together again, but the fact that Lex descended deeper into morally grey territory after “Onyx” left the impression that the evil side was now the dominant personality. In season 7, an exploration into Lex’s consciousness showed the evil Lex murdering his younger self, who was the personification of his diminishing good nature. This was a symbolic moment for Smallville, as it meant that any shred of humanity that Lex had left was now gone forever.

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