Grim Reaper

The Grim Reaper is an Emblem Heartless controlled by Luxord that is found in Kingdom Hearts II. It is one of the bosses at Port Royal. By exploiting the Medallion, the Grim Reaper can become undead and invulnerable to attack.

Kingdom Hearts II
A Heartless that appeared in Port Royal, it was said to be born from the curse of the Aztec gold.

Using the curse to become undead, it became a ghoul, making it hard to be defeated.

Kingdom Hearts II
When Sora, Donald, and Goofy return to Port Royal to search for Organization XIII, they discover that the Aztec treasure has once again been stolen and that Jack Sparrow has become an undead. They head towards Isla de Muerta to investigate, but are confronted by Luxord, who summons the Grim Reaper to attack them. Though they throw it off the Black Pearl and into the sea, Luxord has his Gambler Nobodies steal some of the medallions. This activates the curse on the Grim Reaper and allows it to revive and knock the heroes onto the Interceptor, which Luxord then sinks with cannon-fire. Once Sora and his friends get to land and recover the medallions, they come to the decision that Luxord must have taken the chest of medallions head back to town. They follow him there, where they find the chest and an undead Grim Reaper. They manage to defeat the Grim Reaper, removing the curse on Jack, but Luxord takes the monster's heart to Kingdom Hearts and escapes through a Corridor of Darkness.

Strategy
The Grim Reaper is first fought on the Black Pearl. It is a simple fight. It doesn't attack much and by now you will be at a high level. Use a combo attack, followed by a Drive. It is a good idea to have Donald & Jack Sparrow in your party.

The second battle is harder. The Grim Reaper can absorb the cursed Aztec Gold and become invincible. Use the Reaction Commands Hinder and Loot Launch to stop it, and Return to return the treasure to the chest - each command will restore 150 coins. To nullify its magic, it is best to use Thunder.

When all of the gold is returned to the chest the Grim Reaper will be vulnerable. Attack and repeat. Be forewarned, though: the Grim Reaper has a tendency of constantly taking the coins for its own. It also has an attack that it automatically empties the entire chest and transforms into a giant. It stomps around the field before delivering one strike to the ground and reverting to normal size. At this point, it'll be a little longer to nullify it's invincibility as you'll need to strip it of all the coins.

Trivia

 * The Grim Reaper's appearance, minus the pendulum, appears to be based on the Aztec god of death, Mictlantecuhtli.
 * Although game play in the American version of Kingdom Hearts II was edited so undead pirates wouldn't catch on fire, the Grim Reaper still catches fire.