According to the Universal Studios website, here is the list of films:
Dracula (1931), Dracula's Daughter, Son of Dracula, House of Frankenstein, House of Dracula, Abbott and Costello Meet Frankenstein, Frankenstein (1931), The Bride of Frankenstein (1935), Son of Frankenstein, The Ghost of Frankenstein, Frankenstein Meets the Wolf Man, The Wolf Man (1941), Werewolf of London, She-Wolf of London, The Mummy (1932), The Mummy's Hand, The Mummy's Tomb, The Mummy's Ghost, The Mummy's Curse, Abbott and Costello Meet the Mummy, The Invisible Man (1933), The Invisible Man Returns, The Invisible Woman, Invisible Agent, The Invisible Man's Revenge, Abbott and Costello Meet the Invisible Man, Creature From the Black Lagoon, Revenge of the Creature, The Creature Walks Among Us, Phantom of the Opera (1943)