"This legend was sealed away because of his power. Now he defies time to challenge you!"
First appearing as the final boss of a sub-game in Kirby Super Star Ultra, Meta Knightmare Ultra, you had to play as Meta Knight and defeat him. An unknown warrior from a forgotten era claiming to be "the most powerful warrior in the galaxy," Galacta Knight possessed great power. He is considered the Yin to Meta Knight's Yang (Much as Marx was to Kirby) and had most of Meta Knight's basic moves as well as a slew of new, more powerful ones.
In Kirby's Return to Dreamland, he appears yet again as a boss in the True Arena, but oddly enough also is mentioned in Story Mode. If you talk to Magolor after collecting all 120 energy spheres, he mentions how he actually knew about Kirby before he even met him, revealing that "there is someone that he knows in particular who knew you fairly well." This is believed to perhaps be Galacta Knight, since the background of the place you fight him in looks similar to the dimension where Magolor lives.
Galacta Knight also plays a more expansive role in my current fanfiction, the Legendary Kirby, where he is the leader of a large army that tried to conquer the universe in the past.
This was a piece that I've been working on since June, and my favorite part of it is probably the effect I gave to the wings and the background, using the paintbrush tool in SAI. I'm also quite fond of his glowing pink eyes here, they just look so distant yet really sinister.