TV Shows:
* Avatar: The Last Airbender: This beloved series premiered on Nickelodeon and gained immense popularity.
* Foster's Home for Imaginary Friends: This quirky and imaginative show continued its run on Cartoon Network.
* The Grim Adventures of Billy & Mandy: The dark humor of this show continued to entertain on Cartoon Network.
* The Amazing World of Gumball: This unique, animated series debuted on Cartoon Network.
* Jimmy Neutron: Boy Genius: The popular Nickelodeon show continued with new episodes.
* Codename: Kids Next Door: This show continued its run on Cartoon Network, with the final season premiering in 2008.
* The Backyardigans: This show, featuring musical numbers, premiered on Nickelodeon.
* SpongeBob SquarePants: This iconic show continued its long run on Nickelodeon.
Movies:
* Shrek 2: The sequel to the popular animated movie was a huge success.
* The Incredibles: This superhero movie from Pixar was a critical and commercial hit.
* Shark Tale: This animated film from DreamWorks featured a star-studded cast.
* Polar Express: This film, using motion capture technology, was released in theaters.
* The SpongeBob SquarePants Movie: The first full-length feature film for the popular cartoon.
Other:
* The Batman: This animated series began its run on Cartoon Network.
* Foster's Home for Imaginary Friends: Destination Imagination: This movie featured a brand new story for the popular series.
* The Fairly OddParents: Channel Chasers: This animated movie was based on the popular Nickelodeon show.
This list is not exhaustive, and there are many other cartoons that premiered in 2004. You can find more information by searching online for "cartoons released in 2004."