Eureeka's Castle is an American children's television series which aired on Nickelodeon's Nick Jr. block from September 4, 1989 until 1995. R.L. Stine developed the characters and was the Head Writer for the episodes. The program featured various puppet characters who live in a Giant's wind-up music box.
The show was a joint development by Nickelodeon, animators Kit Laybourne and Eli Noyes of Noyes & Laybourne Enterprises, and the puppeteers at 3/Design Studio.. Reruns of the show aired on Noggin from 1999 to 2002.
The show follows various puppet characters (in the style of Sesame Street), including Eureeka, a sorceress-in-training. Eureeka and her friends live in a wind-up castle music box owned by a friendly giant. Other characters include Magellan the dragon, Bogge and Quagmire, Batley the bat, and Mr. Knack. There are also various appearing creatures such as mice, singing fish statues called the Fishtones, Magellan's pets Cooey and the Slurms and Batley's pet spider, Webster.
- Eureeka: The title character. Eureeka is a friendly sorceress-in-training. Her spells are not successful most of the time, but she keeps trying until she gets it right.
- Magellan: A large green dragon with a tail that has a mind of its own. He doesn't always understand new concepts. Magellan tends to make great big sneezes that can shake the whole castle whenever he gets upset.
- Batley: An egotistical clumsy blue bat who wears glasses due to being near-sighted. Despite being different in every way, he and Magellan are good friends. His flying usually ends with a crash landing prompting him to say "I meant to do that". Batley spends most of his time in the belfry and has a large bug collection. In a 2016 Reddit AMA, Stine said that Batley's face was modeled after his own son, Matt.
- Bogge and Quagmire: Know as the "Moat Twins", they are siblings who spend most of their time swimming in the castle moat, eating peanut butter sandwiches, and playing in the basement. Bogge is orange and has two arms while Quagmire is pink and has four arms. They tend to argue with each other, but work together when it comes to causing trouble. Bogge and Quagmire constantly try to steal Magellan's peanut butter sandwiches, but never succeed.
- Mr. Knack: The castle's handyman and tinkerer. He uses many unconventional methods for fixing things around the castle. He also loves to barter when he sells some of his inventions that he has made from his pushcart. Mr. Knack always gets some postcards which he reads to the viewers.
- Sir Klank: An old blue mouse with a long gray beard who resides in a suit of armor.
- Kate: A pink mouse who frequently reports on what happens in the castle.
- Emma: A fat orange mouse who loves to eat.
- The Fishtones: A trio of singing fish in the form of a stone fountain who spray water when they're not singing.
- The Giant: A friendly, full-bodied giant with a long nose who owns the wind-up castle music box where the show takes place.