The Batman also received a spin-off comic book series – "The Batman Strikes!" – published by DC Comics. The spin-off comic books were set in the same continuity and style as "The Batman". The man known as Batman, the costumed protector of Gotham City, is secretly billionaire playboy, Bruce Wayne (voiced by Rino Romano). Batman began three years prior to the start of the series, and the Gotham City police do not publicly acknowledge the vigilante's existence. Operating out of a secret lair underneath Bruce Wayne's mansion — known as the Bat cave — Batman and his butler, Alfred Pennyworth (voiced by
Batman: The Animated Series as the Mad Hatter, David Warner as Ra's al Ghul, Michael York as Count Vertigo, Kate Mulgrew as Red Claw, George Murdock as and George Dzundza as the Ventriloquist. One of the series' best-known inventions is the Joker's assistant, Harley Quinn, who became so popular that DC Comics later added her to mainstream Batman comic book continuity. The Penguin underwent change for the series; his appearance was remodeled after the version seen in "Batman Returns", which was in production simultaneously with the series' first season. New life was also given to lesser-known characters for the series such as the Clock