Masters of the Universe (commonly abbreviated to MOTU; and sometimes informally referred to as He-Man, after the lead hero) is a media franchise created by Mattel. Among others, it features the characters of He-Man and Skeletor on planet Eternia. Since its initial launch in 1981, the franchise has spawned a variety of products, including six lines of action figures, four animated television series, countless comic series and a film. Designer Roger Sweet claims to be the chief creator of He-Man and MOTU, although this is not officially acknowledged by Mattel. The earliest storybooks and much of the original backstory were written by Donald F. Glut.