Batman: The Animated Series: 10 Best Characters Who Only Appeared In One Episode
6. Calendar Girl - Mean Seasons
While being a character from The New Batman Adventures rather than Batman: The Animated Series, this listing still counts as the series served as a sequel to the original show, being based in the same universe and featuring the same characters.
Calendar Girl is a loose adaptation of the comics villain Calendar Man, though the two really only share their name and use of calendars in their crimes.
The villainess' secret identity is Page Monroe, who turns to a life of crime after her modelling career begins to stumble due to her turning 30. As an act of revenge, Monroe becomes Calendar Girl and kidnaps the individuals who caused the downfall of her modelling career. She leaves clippings from a calendar at each crime, all featuring different dates.
Batman and Batgirl eventually discover Monroe is the culprit behind the crimes, and they stop the rogue before she can enact her "Day of the Dead" plans.
Monroe is an extreme example of how someone becoming obsessed with their appearance is unhealthy, as Batman even states that the former model still looks good, and is the only one to see her own flaws. Truly, a tragic story of a woman driven by the opinions of other individuals which drove her mad.