"You know what happens if we don't kill that thing?! First, we die! Then, EVERYONE dies! It'll eat its way through everything in the universe 'til there's NOTHING LEFT!" -Tara Sachs
Galeem (キーラ, Kiira) is one of the two main antagonists of Super Smash Bros. Ultimate's Adventure Mode: World of Light along with his dark counterpart Dharkon. He is described as "Lord of Light" and the "ultimate enemy" in the World of Light. His goal is to recreate the universe in his own image. He is known to be the overall most powerful villain and being in the history of video games. With no biases or no mortal restrctions. It wants all who live to die at his hands. It wants to rebuild the universe with no place for mortal beings.
World of Light
Prior to the events of the mode, Galeem commands an army of Master Hands. The fighters remain confident. But Galaxia (Tara Sachs) has her sixth sense kick in, having a similar vision like Shulk. She suddenly sicks down on her knees in despair. Some of the fighters get confused on why she suddenly turned terrified. Tara says with a broken hurt voice "We can't fight...this...god... We're going to die...." Galeem turns into a black hole and collapses which launches a devastating inescapable attack. slaughtering all fighters with the sole exception of Kirby and Tara Sachs. A devastated Tara flies away to Kirby in hopes of surviving. A beam of light barely misses her, but it brutally rips off her wings, making her plummet to her doom. As Kirby catches her, they both warp away before a beam could engulf them alive Galeem takes away every non-playable characters' souls. His attack goes on to engulf the entire universe in a burst of light, leaving what is left of the world and galaxy a barren wasteland inhabited by hostile spirits and puppet fighters cloned from the fighters imprisoned by him. Kirby and Tara crash land on a cliff which was the new world that Galeem has constructed. Tara breaks down in tears with what has happened to the fighters, with every strong negative emotion consuming her. Kirby comforts her and the two set out to defeat Galeem and save all who live. Despite Tara being in a poor mental condition to fight, she fights anyway
After Tara and Kirby save Mario, Anna, Capucine, and their leader Twilight, she tells them the story behind Galeem. Galeem is a being who was created by the goddesses of the legendary galaxy warriors in hopes of find ways to bring peace to other people. But what the goddesses didn't know is that it took a life of its own, becoming a power-hunger lunatic as a result. It sought to raise itself higher than the goddesses. It begins to attack the goddesses. They all fought back, knowing that it can't be reasoned with; but Galeem captures every last one of them; not caring who is in its way. Before the leader of the goddesses Twilight is captured, she sends out a a SOS message to all the fighters to gather up at the Isle of Ancients, but her sentence was cut short as she couldn't tell them that they're about to be killed when Galeem captured her along with her comrades. Tara feels enraged hearing about it. Twilight comforts her, saying that her comrades are not LITERALLY dead yet. And before as she was captured, she witness Galeem's attack on the galaxy. And uses her remaining magic to save most non-fighters in their own words and dimensions from Galeem. Twilight gives the five of them their mission. Find the fighters who got engulfed by Galeem, and then hunt him down. Killing him to restore the world back to what it once was and return all who has been "killed" back home alive and well. This will also save the other goddesses.
When enough fighters are saved. They comforted Galeem. Galeem then turns into a black hole, about to launch the same attack to kill all the fighters again. Tara refuses to let that happen and uses up ALL of her magical energy to counter the attack (despite Capucine's warning that if she uses that much energy, her body will overcharge and die; unable to contain the power). Tara manages to create a large barrier to protect all the fighters she saved. And using the remaining magic, she forces it all on Galeem, destroying his black hole and ability to create beams of light. Capucine revives her before she could die of being overcharged and used her newly created enchantments to give everyone the ability to kill a god just by using their normal weapons. After Galeem's first defeat, Dharkon appears along with his army of Crazy Hands, driving Galeem away. Galeem later returns when Dharkon is defeated and flees into a dark portal, with Galeem in pursuit.
In the final world, Galeem wages war with Dharkon, while also seeking to destroy the fighters. The true ending can be obtained by defeating both Galeem and Dharkon. Both Galeem and Dharkon are finally defeated by the fighters. But not before Tara unleashed her ultimate suicidal attack (she somehow survived her kamikaze attack); hell-bent on killing on them both, sinking into the ocean and exploding thereafter, and all the souls they stole returned to their homes. Tara lets out all of her tears, making the other think Tara should have some time away and her there for her, knowing her emotional recovery will be such a long and painful process.