Simpson started off in British comics such as Warrior and 2000 AD, and has since illustrated comic books for such industry heavyweights as DC Comics and Marvel Comics.
He has worked on such comics as Batman, Judge Dredd and John Constantine of Hellblazer.
Since 2000, like numerous other A/P/AVP alumni, Simpson has done a lot of work as artist for the film industry. This has included storyboarding for the films City of Ember and Closing the Ring, and illustrating animated films.
He is also partner with his brother Ken in the Belfast based animation company Rogue Rocket.