Gerhard was born on April 14, 1959 in Edmonton, and started his association with Dave Sim's Cerebus with issue #65 (August 1984), and continued through its conclusion with #300 in March, 2004. The series was written by Dave Sim, who also drew the foreground figures, and had worked on the self-published series largely solo for the first 64 issues. Gerhard jokingly described his job saying that he "draws tables and chairs behind an aardvark". He is also fond of photography (some later issues of the comic book have covers based on his scenic photos) and sailing.
Effective December 31, 2006, approximately three years after finishing his work on Cerebus, Gerhard ended his professional and personal relationship with Dave Sim. Subsequently, Dave Sim has been in the process of purchasing Gerhard's share of Aardvark-Vanaheim.
Although most associated with Cerebus, Gerhard has produced works for other publications, although mostly with Sim