Why Palpatine Killed Plagueis Before Learning Immortality (Legends)

Everyone knows Emperor Palpatine as the master manipulator who brought the galaxy to its knees. But before he became the all-powerful Sith Lord of the Empire, he was an apprentice—Darth Sidious—serving under a Muun known as Darth Plagueis the Wise. Plagueis wasn’t just any Sith; he was obsessed over mastering life and death itself. So why would Palpatine kill his teacher before learning the very secret of immortality he had been searching for?

The Master Who Wanted To Cheat Death & the Apprentice Who Wanted Everything

Darth Plagueis, born Hego Damask, wasn’t the kind of Sith who just wanted to conquer planets. He wanted to conquer death itself. He believed that if he could control the midi-chlorians, he could manipulate life—create it, sustain it, and keep it from fading away.

From early on, Plagueis was convinced that through science and the Force, he could finally bring stability to the galaxy and end the endless cycle of Sith destruction. Over the years, his experiments grew darker. He used the Force to influence midi-chlorians, even managing to resurrect a sentient being at one point. For him, immortality was close to becoming real, not just theory.

At his side was his apprentice, a young and ambitious politician from Naboo. Sheev Palpatine watched, learned, and pretended to serve. To Plagueis, this was the perfect partnership. To Sidious, it was a temporary arrangement.

Plagueis imagined a future where he and Sidious would rule together—one in the shadows, one in the light. He would be the hidden master, and Sidious would be the face of the Sith’s new empire. That plan sounded perfect to him, but Palpatine had other ideas.

He didn’t want to share control of the galaxy with anyone. The more he learned from Plagueis, the more he saw himself as the true heir to the Sith’s destiny. To Sidious, power wasn’t meant to be shared or guided but to be absolute.

The Night Of The Betrayal

After years of manipulation and planning, Palpatine finally rose to political power. He became Supreme Chancellor of the Republic—exactly as Plagueis had hoped. When they celebrated together on Coruscant, Plagueis let himself relax. He drank heavily and fell asleep, never sensing the danger beside him.

That night, Palpatine made his move. He unleashed a surge of dark energy, killing his master while mocking him for his arrogance. Plagueis tried to defend himself, but it was over in moments. The man who had nearly mastered life was destroyed by the one he trusted most.

It’s almost poetic. Plagueis could stop others from dying, but not himself. His vision of eternal rule died in the same moment that Sidious’s empire began to take shape.

Why Palpatine Didn’t Wait

Palpatine could have waited a little longer. If he’d stayed by Plagueis’s side, he might have learned the final step toward immortality. But he didn’t, because he was afraid.

Plagueis had promised that their reign would be different. He told Sidious they would be free of the Rule of Two, that they would rule as equals with no secrets or betrayal—two Sith who would finally break the cycle of master and apprentice. But the more Plagueis obsessed over cheating death, the more Sidious saw the danger in that promise.

If Plagueis ever perfected true immortality, killing him would have been impossible. A master who could not die would never be replaced, and the Rule of Two—the very path that allowed the apprentice to rise—would end forever. Palpatine knew that once his master found a way to return from death, he’d be trapped as the eternal apprentice.

That fear drove him to strike first. In his mind, waiting meant losing everything. So he killed Plagueis before his master could become unkillable. Sidious valued control over eternity.

Even after killing Plagueis and claiming ultimate power, that fear never truly left him.

“Uncertainty rippled through Sidious, rage returning to his eyes. A tremor of his own making, or one of forewarning? Was it possible that the wily Muun had deceived him? Had Plagueis unlocked the key to immortality, and survived after all?”

The Price Of Ultimate Power

After killing Plagueis, Palpatine tried to finish what his master started. He studied forbidden techniques, ancient rituals, and dark science. He came close through Essence Transfer, a method that let him move his spirit into clone bodies. But it wasn’t true immortality.

His clones decayed faster each time, unable to contain his dark power. In the end, he survived only through temporary vessels until his spirit finally collapsed. All the power he gained couldn’t stop the inevitable.

Plagueis had searched for immortality. Sidious searched for domination. Both ended up proving the same truth: the Sith could not escape the consequences of their own greed.

The Tragedy Of Darth Plagueis The Wise (Canon)

In Canon, the story lives on as a legend within the galaxy. During the final years of the Republic, Palpatine tells it to Anakin Skywalker at the Galaxies Opera House. He describes “Darth Plagueis the Wise” as a Sith so powerful he could influence the midi-chlorians to create life and prevent death.

He tells Anakin that Plagueis became so powerful that the only thing he feared was losing his power, and that fear became his downfall. “Unfortunately, he taught his apprentice everything he knew. Then his apprentice killed him in his sleep.” Palpatine ends the story with a quiet laugh and one chilling word: “Ironic.”

In this version, Plagueis and Sidious worked together to unlock immortality through science and the Force. Plagueis even attempted to form a Force dyad with Sidious—a unique bond linking two beings as one—but it failed. Eventually, Sidious decided he had learned everything he needed, killed his master, and took Darth Maul as his own apprentice.

Years later, he would use Plagueis’s teachings to cheat death after the Battle of Endor, transferring his spirit into clone bodies on Exegol. Yet, even then, the process was flawed. His body decayed, and his essence weakened. In the end, Rey destroyed him for good. Palpatine himself wondered if perhaps Plagueis was having the final laugh after all.