"Batman" - "The Zodiac Crimes" - January 11, 1967

 The caped crusader's top two challenging villains joined forces in this episode, the first part of a three part story.  The episodes "The Zodiac Crimes", "The Joker's Hard Times" and "The Penguin Declines" featured Cesar Romero as The Joker and Burgess Meredith as the Penguin (Meredith does not appear in "The Joker's Hard Times.")