Caliber Comics started their Oz comic with Issue #1 and ran for twenty issues. However, there were several comic prequals that came out during the run of the original series.
It begins in Issue #0 which shows the Nome King(who is apparently Kaliko since he refers to his "predecessor")leading his troops to Oz for a new peace treaty, but his true intention is to conquer over the entire country with his Nome army and his ally, the wicked Mombi. He takes over the Emerald City, kills Jinjur's husband, turns the Good Witches into ornaments, banishes the Wizard back to Earth, entrances Dorothy, and uses magic charms from Mombi to change Lion, Scarecrow, and Tin Man into his evil minions. Amber Ombi(Omby Amby's nephew)who is the current Captain of the Guard manages to escape. This begins a series of one-shot specials: Scarecrow, Lion, Tin Man, and Freedom Fighters, where Amber rallies the remaining heroes of Oz into a rebellion against the Nome King's forces. This is difficult with the Three Kings now turning their powers against them, including sending other troops after them like ill-tempered Munchkins, Scarecrow's crows, and Tin Man's new tin warriors. The Freedom Fighters consist of Amber, Jinjur, Wogglebug, Tik-Tok, Sawhorse, Gump, Shaggy Man, Jack Pumpkinhead(complete with plant-controlling powers), and a reluctant Scraps.
The Patchwork girl frets over her lover Scarecrow being put under a spell, so she steals the Love Magnet and sets out to free him from the Nome King's control. This becomes the basis for the Romance In Rags 3-issue series. Scraps makes her way to the Scarecrow's new castle made on the ruins of the former Wogglebug College, but her efforts aren't strong enough to stop him from capturing her commrades. The Freedom Fighters manage to free themselves, but Scraps is imprisioned by Scarecrow, and sent to the Emerald City. Now there's two inconsistancies in this part, one is that Romance In Rags ends saying that Scraps is kept in the dungeons for ten years, but escapes immeadiately in the next series, and the other is Dorothy appearing as a teenager while enthralled by the Nome King even though no length of time has elapsed that would age her naturally. The final arc in these prequals is the 3-issue series Straw & Sorcery where Scarecrow is captured by the Freedom Fighters, but escapes, while Scraps herself manages to ellude Mombi's grasp.
This is where the prequals end, and the main story doesn't pick up for about a decade in Issue #1 of the regular Oz comic. There are some dynamic changes in some of the characters in this comic from their original incarnations. Lion, Hungry Tiger, and Wogglebug all look like they might be out of He-Man, Sawhorse seems like a large wooden Clydsedale, and the Gump is a large winged moose. The prequals are currently available in comic format, and online through Drive Thru Comics.