Riddler Name: Edward Nigma First appearance: Detective Comics #140 (October 1948)
The Riddler (Edward Nigma) is a criminal mastermind who has a strange compulsion to challenge Batman by leaving clues to his crimes in the form of riddles, puzzles, and word-games. He often carries a question-mark cane around with him. He recently learned Batman's identity, but kept it a secret to prevent Ghul from learning he had used the Lazarus pits without permission.
Joker Name: Unknown First appearance: Batman #1 (Spring 1940)
The Joker's clownish appearance and big smile hide a devious mind bent on creating as much trouble as possible for his archenemy, Batman. His arsenal of weapons includes razor-cards, acid-spewing flowers, and laughing-gas. He is Batman's most famous adversary, and one of the most recurring.
Ra's Al Ghul Name: Ra's Al Ghul First appearance: Batman #232 (June 1971)
Ra's Al Ghul ("demon's head" in Arabic) is a centuries-old eco-terrorist. He knows Batman's secret identity. He utilizes special pits known as Lazarus Pits which enable him to evade death, and live for centuries. He is the founder of the worldwide League of Assassins, though exactly when this occurred is unknown.
Scarecrow Name: Jonathan Crane First appearance: World's Finest Comics #3 (Fall 1941)
The Scarecrow (Professor Jonathan Crane), an insane psychologist/biochemist, specializes in the nature of fear. Dressed symbolically as a scarecrow, he employs special weapons, equipment, and techniques designed to use fear to his advantage in his crimes. His "fear-gas" stimulates the phobias of his victims. Ironically he has a fear of bats.
Catwoman Name: Selina Kyle First appearance: Batman #1 (Spring 1940)
Catwoman (Selina Kyle) is an accomplished jewel-thief with a taste for luxury. She is extremely agile and acrobatic. Although traditionally considered a villain, she has been portrayed more as an "anti-hero" in later publications.
Former district-attorney Two-Face (Harvey Dent) is obsessed with committing crimes themed around duality and opposites. He makes major decisions by flipping a two-headed coin on which one of the faces is scarred. One side of his face was scarred by a gangster in court throwing acid at him. Over the years, he has reformed at various times, with his face being surgically repaired, only to later adopt the alias of Two-Face again.
Poison Ivy Name: Pamela Lillian Isley First appearance: Batman #181 (June 1966)
Poison Ivy (Pamela Lillian Isley), a former student of advanced botanical biochemistry, employs plants of all varieties and their derivatives in her crimes. She has the ability to control all plant life and can create new henchmen with her mutated seeds. She is immune to all plant-based poisons.
The Penguin (Oswald Chesterfield Cobblepot) is a devious crime-boss who is seldom seen without one of his trick-umbrellas, and performs crimes based on birds. The Penguin uses his nightclub, the Iceberg Lounge, as a front for his criminal activities.
Black Mask Name: Roman Sionis First appearance: Batman #386 (August 1985)
Black Mask (Roman Sionis) was a former businessman who hated both Bruce Wayne and Batman, wore a black mask (hence his alias), and led a vast organization of henchmen dubbed "the False Face Society" until Catwoman killed him. During Batman: Battle for the Cowl, Dr. Jeremiah Arkham (the former owner of Arkham Asylum) was driven insane and subsequently became the second Black Mask.