Olindo, Christina
- Italian illustrator and creator of the vampire comic "Oltre" ("Beyond"). In Italian and English.
- http://www.christinaolindo.com

Onsmith
- Comics, gag cartoons, sketches and photos by Chicago-based artist.
- http://onsmithcomics.com/

Orff, Joel
- Comics and drawings, including the weekly strip Great Moments in Rock 'n' Roll.
- http://www.jorff.com/

Omega
- Artwork, comics, movie reviews, and the occasional rant.
- http://www.omega.i8.com

O'Donnell, Mark
- The work of modern humorist cartoonist.
- http://www.modernhumorist.com/mh/0006/odonnell/index.cfm

Oliver, J. Edward
- Biography, and a showcase of various comic strips created over the past thirty years.
- http://www.orso.demon.co.uk/jeo/