Semper has worked for miscellaneous companies as
Walt Disney Studios,
Warner Bros. Animation and
Hanna-Barbera Productions during a career which has involved the development of projects for
Jim Henson,
George Lucas,
Stan Lee,
Rob Minkoff and others. Semper created the English-language dialogue for two of
Hayao Miyazaki's anime feature films
Castle in the Sky and ''
Kiki's Delivery Service, and co-wrote the screenplay for the live-action comedy Class Act''. During the 1990s, Semper was producer/story editor of
Spider-Man: The Animated Series. which ran from 1994 to 1998. In 2016, he began writing a
Cyborg series for
DC Comics drawn by
Brian Stelfreeze.
Spider-Verse Semper is the first Spider-man artist to involve the storyline of the "
Spider-Verse", also known as the "Spiderman Multiverse". The penultimate and finale episodes of his animated Spiderman series, "Spider Wars, Chapter IV: I Really, Really Hate Clones" and "Spider Wars, Chapter V: Farewell, Spider-Man", respectively, involved
multiple parallel universe Spider-Man characters convening. This marked the first Spider-Man story involving parallel universes. The work later appeared in various Spider-Man comics, cartoons and
films in the early 21st century, such as the
Spider-Verse movie franchise, and
Spider-Man: No Way Home.
Creeporia In 2014, Semper created the family comedy-horror webseries
Creeporia (2014). The character of Creeporia was first introduced in the webseries titled
Crypt of Creeporia, a
live-action/animated blend of humor and horror. The title role in the original webseries was played by Kommerina DeYoung. ==Spider-Man website==