Dr. Girlfriend
Entry on Dr. Girlfriend from the 120% accurate Wikipedia:
Dr. Girlfriend is a fictional character on the Adult Swim animated series "The Venture Bros." Very little is know about her save that her first name is Sheila and that she is a veteran super-villain, serving as second-in-command for many different super-villains and having used an assortment of costumed aliases over the years. It is not even known if she really has a PhD. A former stripper or burlesque performer, she was trained in the art of crime by the half-human, half-machine “Truckules.”
The future Dr. Girlfriend first started out under the alias “Lady Au Pair,” a nanny-themed villain whose henchmen (called “murderous moppets”) were highly-trained dwarfs dressed up as children. Very little is known about her time as “Lady Au Pair,” though Dr. Girlfriend has stated that she was widely feared and respected by all.
At some point, she became Phantom Limb’s number two under the name Queen Etherea, with a very revealing sheer costume which resembles a white version of the one worn by Watchmen Silk Spectre. The working relationship between the two quickly evolved into a romantic relationship, though ultimately it came to an end when Queen Etherea met the butterfly-themed super-villain “The Monarch.” The Monarch quickly seduced Queen Etherea out of her costume and into his bed, culminating in her dumping Phantom Limb for the Monarch.
Rechristened “Dr. Girlfriend” by the Monarch and now wearing Jacqueline Kennedy Onassis-esque outfits (including the former first lady’s trademark pillbox hats and pink Oleg Cassini suits), Dr. Girlfriend would quickly establish herself as the more intelligent and competent half of their relationship. Possessing a level of common sense and skill at villainy that the Monarch utterly lacked, Dr. Girlfriend quietly established herself as the true brains of the Monarch’s operation, due in part to the fact that she single-handedly ran the day-to-day operations of Monarch’s organization to such an extent that Monarch was totally dependent on her.
Also she has a deep manly voice and often suspected to be a transexual who's had a major sex change operation.