ThunderCats (comics) entered the Book of Omens to begin his training and claim his rightful place as Lord of the ThunderCats, but Mumm-Ra uses a powerful spell to keep Lion-O trapped in the book for several years in real time, not "Book" time, and seizes control of Thundera afterwards. In the follow-up mini-series, "The Return" (written by Gilmore and illustrated by Benes, Pimental and Lea), published in 2003, Lion-O returned to Thundera to find it enslaved to Mumm-Ra. Several of the ThunderCats are scattered. Panthro, who was left in charge while Lion-O was away, was forced into slave labor. Tygra and Cheetara
What a Cartoon! company to pay for the whole program. In addition to the eventual spin-offs, the "What a Cartoon!" short "Larry and Steve" by Seth MacFarlane featured prototypes of characters that would later go on to become MacFarlane's massively successful "Family Guy". The "What a Cartoon!" project and its assorted spin-offs brought Cartoon Network more commercial and critical success, and the network became an animation industry leader as the 1990s drew to a close. In 2001, coinciding with the death of William Hanna, Hanna-Barbera Productions merged with Warner Bros. Animation and Cartoon Network opened its own production arm, Cartoon Network Studios, in