If you think about the most notable comic book characters, the ones that come to mind are Batman, Superman, Spider-Man and Hulk. When it comes to comics, female characters rarely get the spotlight. This may be partly due to the fact that most readers and creators of comic books were males in the beginning. If there were any female characters in a comic book, they were designated to the role of the girlfriend or damsel in distress. Early attempts to make strong female characters often were short lived or were eventually put in a lesser role than their male counterparts.
The two earliest strong female characters were Sheena, Queen of the Jungle and Wonder Woman. Wonder Woman became DC's main female character that had the ability to fight side-by-side with Superman, even if she wasn't always portrayed that way. There's no question non-comic book readers today would immediately answer 'Wonder Woman' if asked to name a female comic book character.
With recent attempts at movies, non-comic book readers are most likely familiar with the Invisible Woman or Storm thanks to Jessica Alba and Halle Berry. I do think Sue Storm deserves some respect as being one of Marvel's First Ladies but I don't think you could say she is Marvel's most iconic female.
If I had to name the most iconic female, I would have to go with Elektra. She may not be always in the spotlight or featured in a long-running monthly comic but since Frank Miller introduced her in 1981's Daredevil #168 along with Elektra: Assassin and Elektra Lives Again, she's achieved a certain level of respect. Elektra also had her own series in the 90s and even (unfortunately?) had a live action movie of her own in 2005 after appearing in 2003's Daredevil. There was even a Barbie doll version made.
What about She-Hulk? She's had a few ongoing series and is associated with Hulk. Despite that, I don't think she would be a household name. You would think Jean Grey would be known since she was one of the original X-Men and appeared in the first three X-Men movies. Most people are familiar with The Dark Phoenix Saga, which was also featured in the 90s X-Men cartoon. Perhaps it's her lack of an actual superhero name that's been holding her back. Some might say Mary Jane due to her association with Spider-Man but she's not a superhero.
If anyone comes a close second to Elektra, in terms of non-comic book readers, it might be Spider-Woman. In 2007, the U.S. Postal Service put out a set of Marvel Comics postal stamps. Surprisingly, they didn't include just one female character but two. It was Elektra and Spider-Woman that made the cut. Spider-Woman did have her own animated show in 1979 but she's still no where near having the recognition that Wonder Woman has.
This brings up another question, why is it that Wonder Woman can't catch a break when it comes to live-action? She did have a live-action TV show starring Lynda Carter in the 70s but comic fans have been asking for a live-action movie for years. Also, we all know that the attempt to make a new live-action television show has been squashed. Elektra got a big screen movie but Wonder Woman can't even make it back to television.
The unfortunate matter is female comic book characters don't sell as well as male characters. We had that Bad Girl phase in the 90s that thankfully went away. Because many young male readers enjoy looking at female characters with tight or revealing clothing, it's surprising that female driven books don't sell more. It might be a matter that young readers are intimidated by strong female characters or maybe it's because the male characters often get the spotlight in the major comic book events.
It's just really strange that trying to name Marvel's most iconic female character is so difficult. There was some disagreement in the Whiskey Media office when I asked this question. What female character would your friends or family be able to name if you asked them?