As a child, Campbell was interested in cartoons, rather than comics. He first became interested in comics when, as a teenager, he visited a friend's house, where his friend showed him "Uncanny X-Men Annual" #10, which featured artwork by Arthur Adams, whose style would greatly influence Campbell's own. Campbell, explains, "I immediately went nuts over the book. That book had such detail. The art was fantastic. It just started me going. It just turned me around. All of a sudden I wanted to do this, and I felt I could." Campbell began collecting, purchasing books based on the art, not the title, which he says made his collecting habits somewhat difficult at times.