After the short-lived Ajax-Farrell series, Phantom Lady disappeared from comics except for some Matt Baker reprints in I. W. Publications' Great Action Comics and Daring Adventures. But there were no new Phantom Lady stories from 1955 until 1973. DC Comics had bought the rights to the Quality Comics characters in 1956 which included Phantom Lady.
Her first DC appearance was in Justice League of America # 107-108 during an annual JLA/JSA crossover event. The heroes of Earth's One and Two traveled to Earth-X, home of the Quality characters on a world where the Nazis had won World War II. The super-hero team of this earth included the Quality characters Uncle Sam, Black Condor, Doll Man, Phantom Lady, The Ray, and the Human Bomb. They were known as the Freedom Fighters who were aided by the JLA and JSA in finding the mind-controlling devices that kept the world in submission to the Third Reich. It's kind of corny and if the same premise of a parallel world where the Nazis won WW II were used today, the story would be undoubtedly more sophisticated.
DC took Phantom Lady back to her original yellow and green colors, but retained something of the plunging neckline contributed by Matt Baker (although not as extreme). The Freedom Fighters received their own title in 1976, America's bi-centennial. What better time to return Uncle Sam to the pages of comics as a super-hero? In the Freedom Fighters series the team had relocated to Earth-One. The final issue (#15, 1978) included an origin of Phantom Lady, for the first time.
By 1981 she was a recurring member of Roy Thomas' All-Star Squadron, which took place on Earth-Two during the war years, coinciding with Phantom Lady's original stories in Police Comics. Her past was retconned to make her a cousin of Ted Knight (a.k.a., Starman). It was during this era that the Freedom Fighters relocated to Earth-X where they were later met by the JLA/JSA in 1973.
When all the Earths of the Multiverse were merged into one during the Crisis on Infinite Earths, Earth-X was retconned out of existence. An older, post-crisis Phantom Lady appeared in Damage (1994) in which it was revealed that Sandra Knight had married Iron Munro, whose character was an analogue to the Golden Age Superman in the post-crisis 1940s. Knight served as a government spy during the Cold War and later became head mistress of a school for female spies.
Her students included Dee Tyler who became the new Phantom Lady whose adventures were chronicled in Action Comics Weekly # 639-641. Tyler joined a new version of the Freedom Fighters and died a violent death in Infinite Crisis # 1 (2005).
In the Post-52 multiverse a new version of Freedom Fighters, including Phantom Lady, resided on Earth-10 as a one-panel cameo in the final issue of 52 made clear. To my knowledge we never got to see this team in action. There was, however, another version of Uncle Sam and the Freedom Fighters which resided on New Earth, appeared in two mini-series, and included a new Phantom Lady, Stormy Knight (not a relative of the original).
The last appearance of Sandra Knight, of which I'm aware, was in the final issues of Birds of Prey, vol.2, #14-15. Here an elderly Sandra appears with Black Canary and Lady Blackhawk in a modern adventure which parallels an earlier, but yet untold, adventure told in flashbacks. The flashback story took place in 1950 as Phantom Lady, the original Black Canary, and Lady Blackhawk battle a Nazi war criminal. Manhunter, Kate Spencer, also appears in this issue. She was revealed to be Phantom Lady's granddaughter in Manhunter # 23 (2006).
Since the latest DC reboot, Flashpoint, we now have the new 52 multiverse. Time will tell whether Sandra Knight ever even existed in this new reality.
Now we have a new Phantom Lady, Jennifer Knight, who currently appears in her own mini-series along with Doll Man. Knight is a freelance writer, daughter of investigative reporter Harry Knight who was murdered to keep him from exposing a prominent crime family. Jennifer becomes Phantom Lady to avenge her father's death.
She is aided by Doll Man, Dane Maxwell (the original was Darrell Dane), a techno-whiz, who provides her with a costume and special technology. In addition to being able to cast black light via special gloves, she can also take on a phantom state, project hard light objects, and trap victims in an eerie blacklight nothingness.
The new series is well written by the team of Gray and Palmiotti with very good art by Cat Staggs and an awesome first issue cover by Amanda Conner. The dialogue is good and sometimes hilarious, the story as believable as possible for a super hero comic.
In this series it's revealed that Dane and Jennifer have had something of an intimate relationship that is taken more seriously by Dane, but Jennifer is gradually coming around. The series takes place in Metropolis (like they need another super hero), so it will be interesting to see how all this fits in to the larger DC universe. There is also hope for a revisioned Freedom Fighters since Uncle Sam and the Ray have made a cameo in this series. I've always been a Phantom Lady fan and aside from some of the modernisms I dislike in today's comics, this series is not a disappointment and perhaps the most interesting that I'm currently reading.