In the Mighty Morphin Power Rangers TV series, the departure of Jason the Red Ranger, Trini the Yellow Ranger and Zack the Black Ranger marked the end of the original Rangers. While they supposedly just went off to a "peace conference" in the show, Ryan Parrott and Daniele di Nicuolo gave them a decidedly more adventurous destination in Mighty Morphin Power Rangers #40.
While the Power Rangers use their powers to protect the Earth, the Morphing Grid has protectors all over the universe. The Omega Rangers are an ancient segment of rangers that effectively act as a sort of Jedi on behalf of the Morphing Grid. After Lord Drakkon's attempt to take over the Grid failed, the Grid was saved but to completely repaired. However, Grid energy continued to leak into the universe, altering individuals into powerful beings with no control of their powers. The Omega Rangers were reactivated to wrangle these new altered beings and train them to protect the Morphing Grid and use their powers for good.
The newest group of Omega Rangers have familiar faces in Zack, Jason, and Trini. The longtime Power Rangers on Earth are joined by a new companion named Kiya. Zack, Jason, and Trini keep their respective black, red, and yellow colors as they decided to dawn the Omega Morphers and embark through the cosmos as galactic protectors.
As in the series, their old teammates Tommy, Billy and Kimberly kept their respective roles as the White, Blue and Pink Rangers, and they continued to fight Lord Zedd alongside Rocky, Aisha and Adam. the new Red, Yellow and Black Rangers, respectively.
The Omega Rangers' first mission finds them at odds with an enhanced being by the name of Garrison Vox. They dispatch him rather quickly and take him back to Safehaven, the protected home of the Blue Emissary. who's effectively their new Zordon. The Omega Rangers also tangle with Queen Adriyel after they're ambushed at one of her extravagant parties. The party was a rouse to get the Omega Rangers to bend the knee, an offer which they refuse immediately. After they stop the queen from forcing a dangerous shift in the balance of the universe, their attention is turned back home to Earth.
On Earth, they protect the Mighty Morphin Power Rangers from Zedd's newest hired assassin, Dayne. However, Dayne dispatches the new disjointed Power Rangers and their Power Zords rather easily. Although Tommy was gravely injured during the attack, the Omega Rangers swoop down in their Power Zords to defeat an overgrown Dayne and save the Power Rangers. After Jason sees Tommy broken in a bed, he decides to intervene by taking the Omega Rangers on a rogue mission to Zedd's lunar base.
The Omega Rangers stormed Zedd's lunar base and quickly dispatch of the remaining Putty forces, setting up a duel between the Omega Red Ranger and Zedd himself. Zedd throws everything he has at Jason early in the battle but is defeated quickly when the Omega Red Power Zord is summoned to smash Zedd unconscious. However, their victory is short-lived. Zordon scolds Jason for his intervention back on Earth. Zordon is worried that Zedd's absence will create a cosmic power vacuum in which the winner will be a force that Tommy's Power Rangers won't be able to handle.
While the Omega Rangers are saving the Power Rangers, Kiya finds out that the White Ranger Tommy was also Drakkon in another timeline. Drakkon killed her entire family and she becomes enraged at the fact he's still a Power Ranger. In a fit of rage, Kiya kills the Blue Emissary and starts a group called The Anointed to kill all of the Rangers and become of new guardians of the Morphing Grid.
Now, the Omega Rangers have taken center stage in the ongoing "Necessary Evil" crossover, where the Omega Rangers have reunited with their old teammates to face one of their toughest challenges yet.