This version of Callie Briggs first appeared in the episode "The Dark Side of the SWAT Kats". When T-Bone and Razor are patrolling MegaKat City in their home dimension, a stray lightning bolt hits their Turbokat. This results in sending them to an alternate dimension where evil versions of themselves are not only wanted for just about every crime in Megakat City, but are also working for Dark Kat. Mistaken for the Dark SWAT Kats by Dark Kat, T-Bone and Razor are sent to Pumadyne to steal the Mega-Detonator, a key component for an implosion bomb which the criminal mastermind plans to use to destroy Enforcer Headquarters. When Dark Kat realizes he's been had, he sends the real Dark SWAT Kats to kill their good counterparts and acquire the Mega-Detonator.
When Commander Feral arrests the good SWAT Kats, Callie arrives to break them out due to believing them to be the Dark SWAT Kats. As it turned out, Callie was in league with Dark Kat and wanted Enforcer Headquarters to be destroyed so that no one would stand in her and Dark Kat's plans to takeover MegaKat City. However, Callie becomes enraged when the good SWAT Kats foil the Dark SWAT Kats' attempt to blow up Enforcer Headquarters. She attempts to flee her office only to be arrested by Feral's niece Lieutenant Felina Feral, who felt that the good SWAT Kats were telling the truth about her corruption as well.
Unlike the Callie Briggs the SWAT Kats know and love, this alternate version of Callie is unkind, spiteful, emotionless, and uncaring. Callie was willing to let the Enforcers take in the Evil SWAT Kats since she thought they ruined her and Dark Kat's plans, however, she released them so they can destroy Enforcer Headquarters, so her gang can destroy Mega Kat City. Callie seems to be murderous since she killed an Enforcer commando with a deadly gas.
- She might have been in a relationship with Dark Kat throughout the entire episode.
- The only notable physical difference between the Dark Side Callie and the regular one is that Dark Side Callie's glasses are triangular at the lenses.
- She is a lot similar to Laurel Lance's doppelganger Black Siren where she is the exact opposite of her doppelganger by being more ruthless and sinister.