Mark O'Hare is an American cartoonist who created the comic strip Citizen Dog.
O'Hare is well-known for his work on animated television shows as a writer and storyboard artist for Rocko's Modern Life, Dexter's Laboratory, SpongeBob SquarePants, The Powerpuff Girls and Hey Arnold! . He performed storyboard work on The Ren and Stimpy Show. Throughout the run of the series, O'Hare served as the creative director and supervising producer on Camp Lazlo
O'Hare graduated in Graphic Design at Purdue University and in Animation at CalArts.
While a student at Purdue University in the early 1990s, he drew a strip called "Art Gallery" for the student newspaper, The Exponent.