The original Coda are an all-female warrior society on Khera, forming essentially a political party among the governing factions of that planet. Their closest male counterparts are the all-male Brotherhood of the Blade.
Zealot started her own version of the Coda on Earth when she was stranded on the planet. On Khera the group was based in tradition and honor yet became corrupted by politics and hatred of the High-Lord caste, while on Earth the group became bloodthirsty mercenaries who would kill anyone for money. After several millennia Zealot became disgusted with both factions of it and began a campaign to destroy every last Coda sect and its membership on Earth. There are many but very few are named. Most of the ones that are, were trained specially by Zealot and are even more deadly than the nameless hordes of women that call themselves Coda (though they are deadly in their own right). All members are trained in unarmed combat as well as sword fighting, gunplay, seduction and stealth. Coda warriors are not allowed to surrender and will sacrifice themselves to complete a mission.
Prior to Zealot's departure, the Coda members underwent a ritual using her Kherubim blood that caused them to stop aging.
Zealot recreated the Coda on Earth and before she turned on her students she was their leader, the Majestrix of the Coda.
Grifter is the only male to ever be trained as a Coda on Earth or on Khera. He was trained by Zealot.
Voodoo was a member of the WildC.A.T.S with Zealot and she recieved training but didn't become as skilled a fighter as other Coda have shown themselves to be.
The Grand Sarin is, according to Zealot, the deadliest weapon of the Coda. She was trained by Zealot, wears a special combat suit adorning advanced munitions and carries explosives, special swords and other gadgets. Her real face has never been seen.
Andromache is another Coda trained by Zealot and became the Majestrix of the Coda after Zealot was abandoned by the group.
Nemesis was made a member of the Coda and trained by Zealot at the request of Mr. Majestic.