Millar was the writer of the status quo shattering Civil War.
He is also the architect behind the Millarworld comics. This is a group of comics that are all published by different companies, and the only binding thread seems to be Millar as their writer. These books include Wanted, Chosen, and The Unfunnies. On June, 2008 a film adaption of his "Wanted" series was released. It stars Angelina Jolie and James McAvoy. He was called in and suggested Iron Monger as the main villain for the 2008 film adaption of "Iron Man". His next big project is called "Nemesis" but DC is currently taking legal action against Millar due to the characters likeness to Batman.
He was diagnosed with Crohn's Disease and has since cut back on his workload.
He is also famous for his reinvention of Nick Fury, The Avengers and The X-Men in the "Ultimate Universe", which deals with more modern and cynical versions of the classical "616" universe. He described his style, as taking it back to basics, and giving it a more current day twist. He was the creator of Old Man Logan, who comes from another alternate universe.
Currently Millar is writing the creator owned comic, Huck.