This one may get a little confusing, but here are your choices:* Sandra Knight (Quality / DC comics) - 1st appeared Police Comics #1 (1941) from Quality Comics; later used by DC. Costume was yellow with green cape
* Sandra Knight (Fox Features & Ajax-Farrell version) - Costume was blue with red cape; appeared from 1947-1955
* Dee Tyler - 1st appeared Action Comics Weekly #636 (1989) / died in Infinite Crisis #1 (2005)
* Stormy Knight - 1st appeared in Crisis Aftermath: The Battle for Blüdhaven (2006)
* Jennifer Knight - 1st appeared in Phantom Lady and Doll Man #1 (2012)
Note that there are two versions of "Sandra Knight" included. The first one was in stories published by Quality Comics starting in 1941, but the character had been created for Quality by the Eisner & Iger studio (as in Will Eisner and Jack Iger).
When Quality Comics stopped publishing stories with Phantom Lady, Jack Iger later made a deal with Fox Feature Syndicate allowing them to use the character (which they did starting in 1947).
Then in 1956, DC made a deal with Quality Comics to obtain some of Quality's properties (like Blackhawks) once Quality gave up publishing comic books, and it was thought by DC that they had acquired the rights to characters like Phantom Lady.
Quality Comics version:
Fox Features version:
DC Comics (with other members of the Freedom Fighters) - as seen in Justice League of America #107 (1973)