Invisible woman of Cornelia

The invisible man of Cornelia was an NPC in the original release of Final Fantasy whose sprite was impossible to see due to a glitch in the game's script. The character was nevertheless given a line of dialogue, resulting in an awkward moment in which the player seemed to be talking to no character at all.

The bug was triggered as a result of a mistake in the game's programming: whenever the player enters a room in Castle Cornelia the characters who remain outside of it become invisible to simulate the player's inability to know who remains outside; the characters that were inside the room would become in turn visible. The invisible man's sprite is only visible whenever the player enters a room, but, since there was no room near his sprite, there was no way to ever actually make said sprite visible.

By means of a Gameshark code that allows the player to walk through walls, the invisible man of Cornelia was recently revealed to be a woman.