I haven't looked at too many DC villains here, due to a purely personal bias, but I've got images stacking up on my hard drive, so, yeah. Onto today's installment, then.
Lady Vic. Lady Elaine Marsh-Morton, scion of a proud English line of mercenaries and assassins. She has a battle butler named Bivens and enough exotic weaponry to wipe out a small nation. She fought Nightwing.
That's it. She was one of a number of villains created to go up against Nightwing when he got his own book, appeared fairly regularly in said book, then wound up where every DC villain who isn't the Joker, Lex Luthor or Darkseid goes-the background. She's a face in the crowd, someone to use when you need to fill a gap. It's a shame, because frankly the ingredients are all there to make her the equal to, say, Deadshot in terms of popularity. It's just a matter of opportunity, really.
First off, let's re-consider her motivations. She's already rich, so assassinations and mercenary work have probably slid from being a priority to a hobby with her. Something she does to relax, or to break her out of a self-imposed lethargy, perhaps.
Lady Vic works for the challenge then. The more challenging the assignment, the better she likes it. She needs the thrill to function.
Imagine her being hired by a renegade Atlantean noble to kill whichever member of Aquaman's supporting cast is in charge of Atlantis these days. Or, even better, she's hired by someone with a mania for super-technology (like, say, the Scavenger) to get ahold of Hawkman's Nth Metal harness, Batman's utility belt or any number of items from the Flash Museum.
Since she's essentially a hired gun, she's simultaneously very easy to slot into a given book, and hard to develop beyond that two-dimensional status. Much like Deadshot, she'd probably flourish in a villains-only title. Consider this: Lady Vic puts together a group of like-minded assassin/mercenaries for a particular job, only to run afoul of the League of Assassins or Kobra, forcing the group to stay together. Perhaps they're caught between two factions within an organization, or even a law enforcement agency (such as Checkmate) and a criminal group. Or perhaps Lady Vic is one of a number of voluntary (or involuntary) participants in Roulette's underground fight club.