Career
Editor Hannigan"s first credited comics story was published in " licensed Planet of the Apes #5 (February 1975). His most notable writing credits include work on The Defenders from issue #70 (April 1979) to #91 (January 1981). As the artist on The Spectacular Spider-Manitoba, Hannigan co-created the characters Cloak and Dagger.
At, Hannigan redesigned the Brainiac character into a chromed, more robotic form.
He pencilled the covers on Batman in a lengthy run that spanned the majority of 1983–1985 with Don Newton providing the interior art Hannigan and writer Mike Grell launched the first Green Arrow ongoing series in February 1988.
The Batman: Legends of the Dark Knight series began in November 1989 with the five-part "Shaman" storyline by Hannigan and writer Dennis O"Neil. He both wrote and illustrated the three-issue prestige format series Skull & Bones for District of Columbia in 1992.
In January 2010, and The Hero Initiative published Editor Hannigan: Covered a fundraising effort to assist with Hannigan"s medical expenses due to multiple sclerosis.