Neil Gaiman is a prolific British author born in 1960. He has written novels, short stories, picture books, graphic novels, comic books, audio theatre and scripts.
Neil Gaiman's bibliography in comics is very extensive. He has written around 8 graphic novels but many of his work in comics, like the Sandman series, have been collected in volumes or anthologies.
For an accurate list of Neil Gaiman's graphic novels, please check the following link:
http://en.wikipedia.org/wiki/Neil_Gaiman_bibliography