From CoH Comic Index
"Agent Shadow" was a representative of the original incarnation of Shadowborn when it existed as a secret rogue government operation. She first appears in Issue #4 of the "Guardians of the Dawn Spotlight" series and appears in flashback in Issue #12.
Very little is really known about "Agent Shadow" other than her codename. As with many of her operatives at the time, she disguised herself with bright-colored wigs and sunglasses. But she was best known for her ruthlessness. She was not afraid to do what needed to be done, even if it meant killing innocent people in broad daylight.
Murder of Sally Bright
In 2007, she introduces herself as "Special Agent Shadow" from Homeland Security. She kills computer forensic expert Sally Bright in cold blood and then walks away, leaving the police officers connected to Shadowborn to clean up after her and take the fall. The reasons behind her murder, though, had nothing to do with Homeland Security, but to get information from a mysterious source about a possible threat to her own life. After completing the murder, the informant told Agent Shadow that the person she should be looking for would be Stephanie Walters.
In 2009, Agent Shadow was able to discover that Stephanie Walters was a part of Witness Protection after Stephanie's ex-husband turned state's evidence against members of The Family. Making a deal with a member of the Family willing to cooperate with the government, Agent Shadow then orchestrated a way to have Walters come out of "hiding" and be eliminated without her being involved.
Unfortunately for her, Walters was put under "Tier Two" protection, given a new name as Stephanie Walker-Rodgers, and was even operating as a member of the Paragon City Police Department's Hero Shield Program as the superhero Captain Paragonna.
Pretending to use Walters' family (who were already dead) as bait, Agent Shadow lured Walters to an office building in Perez Park. She also fabricated a story to the media that Walters' ex-husband was suing her for missing child support but without revealing her identity either, forcing the police department to put her on "administrative leave". But she did not count on Walters either disobeying order and arriving as Captain Paragonna, figuring out that the threat of losing her "family" was a ruse, or that she would inform the US Marshalls that their "Tier Two" protection was breached.
With Captain Paragonna shutting down several Family members, an unseen member of the federal government was the one that killed Agent Shadow with a sniper rifle. The Marshalls then oversaw the rest of the dismantling of Shadowborn.
Although dead, Agent Shadow appears again in the year 2010, but according to Montague Castanella of the Midnight Squad, this was a past incarnation of her that was recruited by the same "informant" (later revealed to be Mender Tesseract) to an to aid in the death of Daybright, whose human host she murdered in 2007. She first encounters Captain Paragonna but has no idea who the hero is since she did not yet know that detail. (Captain Paragonna was warned beforehand by Castanella to not act like she recognized Agent Shadow.) She later encounters Daybright, now aided by MidKnight X, and manages to escape defeat at the hands of the newly-reborn Peacebringer, only to later be defeated by MidKnight X and sent back to her timeline.
Agent Shadow apparently has a sister, who contines to operate in her memory as Agent Blue.