Gary Clark went to art school aged 16 in the 1970s and, inspired by Wizard of Id, wanted to create comic strips. He worked in advertising for Myer before becoming a full-time cartoonist.

Clark is most known for the newspaper strip Swamp, first published in 1981 in the Sunshine Coast Daily. It expanded to around 70 newspapers throughout Australia, New Zealand and Europe in multiple languages. The strips have been published in a number of anthologies.

Gary also created Diesel Dog cartoon in Truckin' Life (~1980). Continued by others (Wayne Madden, Steven Bloomfield) for nearly 20 years, Truckin' Life asked Clark to resume the cartoon in 2011.

Gary Clark has won 10 Stanley Awards for Best Comic Strip Artist of the Year and 11 Rotary National Cartoon Awards. His company, Swamp Productions Pty Ltd was nominated for export achievement in Arts/Entertainment in the 1999 Queensland Awards for its export to Japan, including licensing the characters for casual and sportswear.

Clark has written on education and community development in Aboriginal communities.