Dark Mind is a mysterious figure who wanted to conquer the Mirror World, so he corrupted it with his evil. Meta Knight found that this would threaten Dream Land, so he went to the Mirror World. However, he found himself beaten and imprisoned by his evil counterpart, Dark Meta Knight. It was then up to Kirby and his newly-born clones to save Dream Land and the Mirror World, so they ended up there. His appearance suggests that he might be the Mirror World version of Nightmare, Zero, or even both.
Dark Mind's first form looks like an odd cross between Zero and Nightmare, with two mirrors orbiting the villain and a core (probably his true form) below his cloak. His main attack in this form sees him firing a large number of stars in wave or stream formations or constantly teleporting around (much like Nightmare "orb"). Dark Mind is fought more than once, and as phases go on, he becomes more erratic and he gains new attacks, such as dropping stars in corners which later home in on Kirby, swinging his mirrors around in a circular pattern, shattering into glass if attacked when his his core is not exposed, and dropping large bombs that destroy the whole screen if not promptly destroyed. The stars can be inhaled for Fire (red), Ice (blue), Spark (violet), or a random ability (green), and the bomb will give Crash if super inhaled.
Dark Mind will open his cloak for all his attacks: although Dark Mind is always vulnerable, he will take much more damage, stop whatever he is doing, and retreat if he is attacked with his cloak opened. Defeating Dark Mind in the first three battles will cause him to shatter (similarly to Dark Meta Knight, his probable creation), but the fourth defeat will cause him to explode violently and glow white as his cloak vanishes.
Form 2 (Power Orb Form)
The second, most important battle against Dark Mind sees the villain start out as a Zero-like eyeball and grow enormous as it approaches the screen in a red, gaseous area similar to Dark Star's gaseous interior; if Kirby does not have the Master Sword at this point, Shadow Kirby will run into battle and throw it to him. Dark Mind uses a variety of attacks, many of which involve his mirrors (which are themselves vulnerable to damage now). His first, most common, and arguably hardest to avoid attack has Dark Mind slowly floating down the screen with the mirrors moving in an erratic figure 8 pattern around him: after several seconds of being right next to the ground, Dark Mind shoots the mirrors in different dirctions, and they then proceed to cross the screen at random heights: occasionally, one mirror will spawn enemies from the middle of the screen. Dark Mind will sometimes approach the ground and circle the mirrors around himself before sending them off in a similar fashion to his main attack: this is the best opportunity to attack the mirrors, and successfully breaking one will cause it to deal a relatively large amount of damage to Dark Mind but will cause the mirror to break into four damaging cutter blades. Dark Mind can shoot a small laser from his eye at one of the mirrors; the mirrors will deflect the laser back and forth between each other before just letting the laser fly offscreen. Sometimes Dark Mind will prepare a much larger beam from his eye (similar to a vertical version of the one Marx uses) and fire it in various ways: lastly, Dark Mind can flip the screen upside down and use the same screen-destroying bomb used by his first form.
Damaging Dark Mind can be done either by attacking his eye (which is relatively easy to hit but doesn't do much damage) or destroying the mirrors (which does much more damage and interrupts whatever he was doing, but is more difficult and made risky by the fact that the mirrors turn into cutterblades upon destruction). After all his health is depleted, Dark Mind shuts his eye and starts to reluctantly shrink...
Now an unstable, fireball-like form similar in size to Dark Matter, Dark Mind retreats into the sky, hotly pursued by the Kirby(s) (now riding warp stars). Dark Mind acts much like the Power Orb form of Nightmare, shooting out barrages of stars and trying to ram Kirby: he also must be defeated the same way (namely, by shooting a lot of stars at him). Depleting his health will start both his explosion and the credits but not put an end to the battle, with Dark Mind still trying to attack Kirby but not being able to do any damage: the Kirbys can shoot him all they please until he drifts to the center of the screen, where - after several seconds - he finally explodes, finally putting an end to his plan of ruling the Mirror World.
Interestingly, outside of Boss Endurance, a tally is kept of how many times the Kirbys have hit Dark Mind after his health is depleted, and adds 30 to that number when he finally explodes.
- Dark Mind's second and final form heavily resembles Dark Matter and Zero from Kirby's Dream Land 3, and as a consequence Dark Mind is widely speculated to belong to the Dark Matter species. If this is the case, then his name 'Dark Mind' may be a reference to the fact that the Dark Matter race largely operates by possessing others and manipulating them to do their bidding.
- Dark Mind makes a cameo in Kirby: Squeak Squad in an unlockable painting, alongside Nightmare, King Dedede, Dark Matter, and Marx.
- Dark Mind could possibly be the Mirror World counterpart of Nightmare, Zero, or even both of them.
- Dark Mind's first form appears to have 4 eyes as well as two faces, but on closer inspection, the "face" resembling Nightmare is actually a sort of crown worn by him, with his true face residing under it.
- If Kirby attacks one of the bombs, a health bar will show up for it but it won't have a name.
- The second and final forms of Dark Mind resemble the Eye of Sauron from the The Lord of the Rings novel franchise.
- Necrodeus, Dark Mind, Wham Bam Jewel, and Magolor Soul are the only bosses in the series to have exactly three eyes.
- Dark Mind and Magolor are the only final bosses to have more than two forms in one game.