Given "life" by a dying Hyness, Void Termina is arguably the most powerful foe Kirby has ever faced.
He's a giant titan who reminds me a lot of Majora's Mask from the Zelda series. The name Void Termina says it all.
You fly around on the "friend star" or whatever it's called and blast Void Termina while avoiding his energy waves. This is easy enough at first.
Then you have to fight inside his head and see his true (and oddly adorable) form. This is a bit more difficult.
You are sent back to the space battle and Void Termina's giant body grows wings and fights you in the air.
But yet again you'll have to eventually fight the inside of his mind or whatever.
Then it's a epic battle to save the Kirby universe.
And Void Termina is destroyed by the power of Kirby and all of his friends. Too bad you could only fight with three in the actual battle. All that said, Void Termina was one of the best bosses in the Kirby series and one of the better ones in recent Nintendo history.