Matt Wagner's first published comic book work was Comico Primer #2 (1982), which was the first appearance of Grendel. In addition to his creator-owned series Mage and Grendel, he has worked on comics featuring the Demon and Batman as well as such titles as Sandman Mystery Theatre. In 1991, he illustrated part of the "Season of Mists" story arc in Neil Gaiman's The Sandman series.He wrote and drew Batman/Superman/Wonder Woman: Trinity a limited series featuring DC's three major heroes in 2003. He followed it with Batman and the Monster Menand Batman and the Mad Monk in 2006.
His other projects include Madame Xanadu for Vertigo, with artist Amy Reeder Hadley.
He has produced numerous comics covers, including painted ones for Green Arrow and has written several Green Hornet limited series for Dynamite Entertainment.
Outside comics, Wagner provided art for the 1984 Villains & Vigilantes adventure Battle Above the Earth written by Steven Crow