Invisible

The Invisible is a Pureblood Heartless that is found in Kingdom Hearts and Kingdom Hearts 358/2 Days.

Abilities
The Invisible fires dark energy every now and then, and uses its sword to slash at Sora. One of its special attacks includes throwing its sword in the ground, while the main body turns into a ring of dark fire surrounding either Sora, Donald or Goofy. The ring of dark fire appears to circle the person closest to the Invisible. Once the time is up, the curse explodes, dealing large damage on any member of the party. This can be avoided by jumping, using Superglide, or using Dodge Roll. Like Angel Stars, they have a high rate of dropping a Gale once you've defeated them.

In Kingdom Hearts 358/2 Days, the Invisible can still perform its basic slash attack, but is given an "improved" arsenal of abilities from its Kingdom Hearts version. Its "Ring of Fire" attack is upgraded to cause its weapon to fly at Roxas up to five times while the beast is invisible, before surrounding Roxas with the ring and striking down with a long-range shockwave as a result. This Pureblood Heartless will fire a consecutive string of energy spheres, dealing a high amount of damage and possibly lowering Roxas's Defense to Lv. 1. It shares all of its abilities with its relative, the Orcus, a weaker, red version of the Invisible.

Trivia

 * The kanji written on its blade means hard shell.
 * Invisibles have a heart-shaped hole in their stomach, much like a Darkside.