Lady Wantsomore was a character in the Julian Bashir, Secret Agent holodeck program. Felix described her as "a beautiful socialite who's been brainwashed to assassinate the Queen of England".
In 2373 Julian Bashir didn't have to try very hard to convince Jadzia Dax to play the role of Lady Wantsomore. (DS9: "A Simple Investigation")
This character was only mentioned in dialogue.
Her name is a tribute to the James Bond series' tradition of women with sexually suggestive names such as Pussy Galore. (Star Trek: Deep Space Nine Companion (p. 295))