10 Best One Time Only Characters In Batman: The Animated Series
1. The Judge
If you have seen Judgment Day, you will know that The Judge both is and isn't an entirely new character.
Taking a cue from Batman: Mask of The Phantasm, the show introduced The Judge as a new vigilante who takes a far more fatalistic approach than the Dark Knight.
Using corrupt politician, Councilman J. Carroll Corcoran to track criminals down, The Judge defeats The Penguin, Killer Croc, and The Riddler, before setting his sights on Two-Face. When this fails, The Judge tries to kill Corcoran, by which time Batman knows The Judge's true identity.
The Judge has a very ethereal presence throughout the episode, not unlike The Phantasm. The character is even voiced by Malachi Throne, who portrayed False Face in the Adam West Batman TV series. Throne's casting is a nice little red herring, which helps to convey a sense of dread to Gotham's criminal underworld, whilst maintaining the mystery surrounding the character's true identity.