Darkseid (Smallville)

"I can see it. Underneath all of that bravado, you're afraid you'll never be the hero you want to be. You wish you could kill me. And I'm not the only one. I can see that. You've felt this way before. Your heart is racing. You're at war with yourself. The turmoil is overwhelming."

- Taunting Clark, "Supergirl"

Darkseid is the main antagonist of the tenth and final season of Smallville, and therefore the show's final antagonist.

Darkseid first appears at the end of the Season 10 premiere "Lazarus," materializing on the crow's nest and roaring skyward. In "Supergirl," he possesses radio show host Gordon Godfrey and uses him to spread propaganda about superheroes, turning a majority of the public against them. Lois Lane seeks to discredit Godfrey and corners him in Club Desaad, a fetish club where she snaps photos of him cavorting with two latex-clad women. Darkseid emerges within Godfrey and takes Lois captive, intending to use her to lure Clark Kent to him. The ruse works, and Darkseid taunts Clark about his inner doubts, sensing that Clark nearly killed someone before and that he wants to do the same to Darkseid. He vacates Godfrey's body and prepares to possess Clark, only to be warded off by Kara Kent using her Kryptonian bracelet.

In "Patriot," Darkseid is revealed to have been marking certain individuals (such as General Slade Wilson) with the Omega symbol.

At the end of the episode "Scion," Darkseid materializes before Lionel Luthor after the latter visits Lex Luthor's grave and expresses a wish for his son to be returned to life.

The penultimate episode "Prophecy" reveals that Darkseid had a son named Orion whose bow Oliver Queen goes in search of in order to remove his own Omega symbol.

In "Finale," the planet Apokolips begins to descend upon Earth. Tess Mercer is captured by Lionel, who plans to transplant her heart into LX-0, a clone of Lex manufactured from different body parts taken from other clones. Tess, however, manages to get free, shoot Lionel, and escape. As a mortally-wounded Lionel crawls toward LX-0 in a secret room, Darkseid materializes and Lionel asks him to return Lex to life; Darkseid agrees in exchange for Lionel's soul and rips out Lionel's heart, which he then puts into LX-0's body, restoring Lex to life.

Later, Darkseid possesses Lionel's corpse to confront Clark in the Kent barn. After a tense verbal standoff in which Clark bravely vows to defend humanity against him, Darkseid telekinetically strangles Clark and declares that he will lose his soul and that he (Darkseid) will annihilate him. Darkseid then throws Clark through the air, but Clark, after experiencing a vision of Jor-El showing him all the trials he's been through over the last ten years, finally gains the ability to fly and flies right through the entity and his vessel, seemingly killing him.

Later, after donning the Superman costume, Clark flies toward Apokolips and pushes it away from Earth, sending it back into space and removing the Omega symbol from everyone.

Quotes
"I can see that you're pure of heart. It's too bad. Taking over that body would have been fun."

- To Lois, "Supergirl"

"That's too bad. Her idealism and blind faith in the vigilantes she loves has gotten her in way over her head."

- To Clark, "Supergirl"

"Are you sure you can win against me? You know what I am. You know the doubt in your heart. You so-called heroes are false gods, all of you. And when people stop believing in you, you'll shatter like glass."

- To Clark, "Supergirl"

"There is darkness in you and great power. I think we'll go far together, you and I."

- To Clark, before attempting to possess him, "Supergirl"

"You refused me once, but this may be the moment when you'll reconsider my offer."

- To Earth-2 Lionel, "Finale, Part 2"

"The lost son of Jor-El. [...] There must be a part of you that's disgusted by how easily your people fell to me."

- To Clark, "Finale, Part 2"

"Is it? Eons have passed since I came face-to-face with a force that could possibly tip the balance to the light. [...] You are the light! You cast out the darkness from Oliver Queen, and you will obliterate my darkness from the rest of the world if you are not stopped! You will surrender to me. You will lose your soul. I will annihilate you!"

- To Clark, "Finale, Part 2"; also his last lines