Formerly a production assistant and eventually production coordinator on the television series Seinfeld, J.T. Krul started a career as a comic writer in 2004 and found a home at Aspen MLT. He became a prominent writer for the company, writing numerous Fathom and Soulfire series. Krul wrote so many issues of each that he became the major writer for both mythologies.
While writing for Aspen MLT, Krul slowly became more and more known at DC Comics. He worked his way in writing short one or two issue stories for JSA Classified, Titans and Joker's Asylum: Poison Ivy. This soon led to him writing the Blackest Night: Titans tie-in limited series for DC's Blackest Night event.
In his first major work for DC, he was given the reins of the Green Arrow franchise and wrote the Rise of Arsenal and Fall of Green Arrow story arc that explored the consequences of Roy Harper's mutilation and Lian Harper's death in Justice League: Cry for Justice. It was a story direction that was widely criticized and unpopular before he even began. Justice League: the Rise of Arsenal, which featured Roy falling back into his drug addiction, quickly became the target of ridicule and outrage for the very dramatized depiction of Roy's intoxicated state and the graphic nature of how it recounted Lian's death. Despite this, Krul went on to be the regular writer the Brightest Day relaunch of Green Arrow.
Krul also became the new regular writer of Teen Titans around this time, teaming with Nicola Scott to stabilize a book that had struggled to find its solid footing after Geoff Johns' departure years earlier.
A little over a year after taking over Green Arrow and Teen Titans, DC's Flashpoint event brought about a mass relaunch of all of DC's titles, bringing an end to the runs that came before. However, it was announced that Krul would not be done with Green Arrow and would be the writer on the relaunched Green Arrow series. Along with that, he was named the writer of ,.a new Captain Atom series.
In October 2011 he revealed he would by leaving Green Arrow after issue 3 and was replaced by Dan Jurgens & Keith Giffen but he said he would continue to work on Captain Atom.
Some Created Characters