The dead character glitch is a glitch in Final Fantasy XII that involves dying during an Esper's Dismiss command animation, right when the character's action is about to begin, trapping them in a state of being flagged defeated, but remaining on the field, standing in place, not doing anything. Having a character like this on the field causes the enemies' special attacks being delayed indefinitely, rendering the enemy completely harmless.
Any attack that prompts the "X is readying Y" message to appear to the top of the screen, works, and is delayed forever. This glitch won't work against enemies that don't use "special attacks", but use only "normal" attacks, meaning this trick works against Yiazmat but not against Omega Mark XII.
The glitch is tricky to perform because the timing is so precise. The easiest way to deliberately cause the glitch is by employing the Petrify status, because petrified characters are flagged as defeated and is essentially the same as the KO status.
The player must first inflict Petrify on a character who has an Esper and who has their gambits turned off. Petrify in Final Fantasy XII works like Gradual Petrify in the other Final Fantasy games, and sets a time limit before that character turns into stone. The player can get the Petrify status simply by using a Gold Needle with the Nihopalaoa accessory equipped.
Once the counter is in place the character must summon an Esper and right before the petrifying counter reaches one, the player must activate the character's gambits, with a gambit where the character uses a mote of some kind onto themselves (any item that has a delay before being used works) as the first priority. Self: Holy Mote/Scathe Mote/Dark Matter will work. The player must then dismiss the Esper.
When the counter is almost at 0, the player must open and close the menu until the number 0 appears on the character. The player must then enter the menu and change their equipment, such as by removing the character's weapon.
If the timing is right, the character reaches the action stage just before being petrified, and the glitch activates. Normally petrified characters simply disappear off the screen, same as KO'd characters, but with the glitch the petrified character will remain on the screen, albeit not doing anything. If the player then kills all the other characters normally, the game will not end in a Game Over, but will instead freeze.
This glitch works in all versions of the game.