The Penguin: Waddling purveyor of fowl play. He puts on a gentlemanly facade and high-class airs. Despite his criminal record he easily insinuates himself into high society and is a known Casanova due to his charms. He is rarely seen without a cigarette holder and one of his trick umbrellas.
Louis the Lilac: A ruthless floral mobster. His goal is to corner the flower and perfume markets through means both legal and illegal. Louis owns several flower shops as front businesses and keeps a well-tended greenhouse of exotic plants. He uses mind control devices, as well as plant-derived poisons and a man-eating lilac.
Aunt Hilda: Marsha, Queen of Diamond's witchy aunt. A former chemistry professor fired for experimenting on the student body, she now contributes to Marsha's schemes with her 'magic' potions. Hilda is more interested in having fun than any real profit and is herself not particularly sinister. She keeps a pet named Mortimer, a hideous serpent-like creature who appeared after she left a potion in her cauldron overnight. Hilda has high hopes for her great-nephew Jonathan Crane, an up-and-coming graduate student at Gotham University.
Bookworm: A frustrated writer who turned to crime after he discovered he was unable to create original material. While he has an educated, soft-spoken demeanor a frustrated scheme can throw him into a violent rage. He has an eidetic memory for text and often quotes lines from famous literature.
False Face: A masterful disguise artist. He can perfectly imitate anyone through masks and costumery. No one knows what his real face looks like, as he wears a mask even when he's presenting as False-Face. The notes he leaves at the scenes of crimes are 'backwards', the opposite of the message he's actually trying to convey. Also goes by the name Jane Doe.
Molly: Professional henchgirl, and a bit sharper than the average mook. She is a former member of the Molehill Gang. While her most common employer is the Riddler she's done services for a number of Gotham's archcriminals under different themed names.
Batman and Robin: The Caped Crusader and the Boy Wonder, defenders of law and order. Not huge fans of anyone listed above. While they routinely find themselves seemingly helpless in the villains' clutches, they always manage a contrived last-minute escape and bring the criminals to justice.
Commissioner Gordon and Chief O'Hara: Heads of police in Gotham City. They find themselves quite unable to deal with the city's waves of costumed criminals. Gordon near-worships Batman as his city's salvation and both are very loyal to the Dynamic Duo.
Alfred: Loyal butler to Bruce Wayne and caretaker of Wayne Manor. He also provides support to Batman and Robin in their heroic endeavors.