Karl Bollers is a former head-writer for the Archie Sonic the Hedgehog comic series, usually sharing writing duties with fellow head-writer Ken Penders. Bollers is one of the few writers who has been credited with defining several aspects of the Archie Sonic universe having handled a sizable bulk of stories from 1999 to 2004.
- Arthur Mongoose
- Ash Mongoose
- Bertha Kintobor
- Colin Kintobor
- Dr. Finitevus
- Eddy the Yeti
- Hope Kintobor
- Hugo Brass
- Isabella Mongoose
- Ivo Kintobor
- J.J. Moto
- Jane Doe
- Jeff, Karl, and Konor (not named in story)
- Jeffrey St. Croix (originally known as Evil Geoffrey St. John; later renamed by Ian Flynn)
- John Doe
- Kage Von Stryker
- Knothole Knuts
- Lady Agnes
- Mayor Bullyani
- Mecha Robotnik
- Mecha Tails
- Megan Acorn
- Mes Braves Battalion
- Mina Mongoose
- Miriam Day
- Nate Morgan
- Order of Ixis
- Paladin Team Sigma-Alpha 2
- Karl Bollers published a number of plans he had intended to implement in the comics following issue #134 of Archie Sonic the Hedgehog that were ultimately never used (2), including:
- Sonic and Amy becoming a couple after being stranded at sea together and keeping it a secret from Princess Sally.
- Tails reuniting with his parents by traveling into space on a modified Tornado.
- Amy's origins being explored in a fuller adaptation of Sonic CD.
- Knuckles departing Angel Island after learning that his presence exposes the location of the Master Emerald, going on a global pilgrimage to learn martial arts, and battling a Dr. Eggman controlled-Monkey Khan while under the control of the Iron Queen before discovering the Master Geode.
- Sally being a pawn in a villainous plot by the corrupted Source of All and Ixis Naugus to prevent the future first previewed in Sonic In Your Face.
- Bunnie and Antoine breaking up due to a change in Antoine's personality, with Bunnie's origins later being explored and her true name being revealed as Scarlette O'Hare (which may have served as the inspiration for Scarlette Rabbot and Bunnie's codename when she was in the Metropolis Egg Army).
- Antoine gaining his scar due to an accident with a knife and becoming a villain after allowing himself to be possessed by a corrupted Source of All in hopes of winning Bunnie back.
- Rotor retiring from field duty in order to pursue a role analogous to that played by "Q" of James Bond fame.
- The Source of All surviving Robotropolis' destruction and reconstituting itself in a remote mountain range, beginning to exert control over King Max, brainwashing the Arachne and another group of Spiders known as the Strand, and possessing Antoine while under the control of Ixis Naugus.
- Locke and Lara-Le putting aside their previous disputes to help raise Knecapeon "Kneecaps" Mace after his father Wynmacher ends up in the Egg Grape Chamber.
- Robotnik kidnapping Hope Kintobor under the pretense that he is the only correct choice to be her legal guardian, while genuinely using her as bait to lure in Shadow the Hedgehog.
- Ixis Naugus attempting to return by transforming Max's body into a duplicate of his own, only to be thwarted by the destruction of the Crown of Acorns
- Mammoth Mogul beginning to age rapidly due to his original Chaos Emerald running out of energy, forcing him to seek out alternative sources through illicit archaeological expeditions and hiring mercenaries like Nack the Weasel. The Master Geode, a powerful gemstone that would fulfill Mogul's needs, would be contested by him, the Iron Queen, Robotnik, and Rouge the Bat.
- Nate Morgan surviving the destruction of Robotropolis, being De-Roboticized by the Bem, and returning as Coconuts' amnesia-addled ally, who creates a new Metal Sonic, Metal Amy, Metal Knuckles, and Tails Doll that are mistaken for Robian versions of the heroes.
- Snively taking up a fifteen foot-tall mechanical battlesuit and the alias "Skarkus" in pursuit of revenge against Robotnik for leaving him alone against the Xorda, leading to an alliance between him and Shadow.
- A.D.A.M. and NICOLE becoming romantically involved, leading to A.D.A.M. seizing control of the Shadowbot army and leading them from New Megaopolis to Knothole.
- A new Dingo Regime leader named Colonel Mange being introduced, with Croctobot, Jack Rabbit, and Gala-Na being reintroduced as Robotnik Sub-Bosses over Downunda, the Great Desert, and Albion. This would have led to the disappearance of the Downunda Freedom Fighters and a confrontation involving the Mercian Freedom Fighters.
- Evil Sonic coming to enjoy impersonating Sonic and enjoying the love of his parents and adulation of his people, leading him to plan to eliminate Sonic and permanently take his place.