Riddler and Penguin Must Reads
For The Riddler
Detective Comics 140 (1st Appearance)
Detective Comics 142 (Crime’s Puzzle Contest!)
Batman 171 (The Remarkable Ruse of the Riddler!)
Detective Comics Annual 8 (Questions Multiply the Mystery!)
Secret Origins Special (When is a Door?)
Detective Comics 705-707 (Riddler/Clue Master Arc)
Batman 292 (Where Were You the Night Batman Died? Testimony of the Riddler)
Batman Chronicles 3 (Riddle of the Jinxed Sphinx)
Detective Comics 822 (E. Nigma, Consulting Detective!)
For The Penguin
Detective Comics 58 (One of the Most Perfect Frame-ups First Appearance)
Batman 51 (Pee Wee the Talking Penguin!)
Detective Comics 87 (The Man of 1000 Umbrellas!)
Batman 27 (The Penguin’s Apprentice)
Batman 25 (Knights in Knavery Team up with Joker)
Detective Comics 99 (The Case of the Temporary Murders)
Detective Comics 126 (the Case of the Silent Songbirds)
Batman 169 (Partners in Plunder!)
Secret Origin Special (Bird of Ill Omen)
Detective Comics 568 (Eyrie)
Detective Comics 610-611 (Snow and Ice)
Batman 448/Detective Comics 615/batman 449 (The Penguin Affair)
Batman Annual 11 (Love Birds)
I would add Gotham Underground to this for both of them, it perfectly shows their friendship and how they interact with each other







