One of the biggest challenges of Marion Cottilard's character is that while the credit's list her name as "Mal" the whole time it sounds like DiCaprio is referring to her as "Mol."
To make matters worse, some places (like wikipedia) list her name as "Mallorie" although no where do I have any recollections of her having this name in the film, nor can I find any solid reason for us to assume this is her name.
General Name Meaning
Mal is a pretty common Latin root that means bad, as a result French, Italian, Spanish speakers will quickly be able to identify that this name means bad.
And don't discount that a parent would name a child "bad" or a form of that, because...well, people still name there kids Mallorie or Mallory, and could easily call there child Mal for short. Not to mention the name Mallory means "unfortunate" or "unlucky."
Marion Cottilard's inception character can easily be viewed through these windows of either bad or unfortunate.
Clearly, when Mal invades the subconscious of her husband Dom Cobb she's always "evil" by ruining his plans, attempting to shoot him, shut down his mission, and foil his plans.
Mal (if she's Mallorie) can also be looked at through the lends of being "unfortunate" as she appears to have been a very pleasant person before her death, and before the inception was performed on her, causing her to loose a grip on reality.
This is the easy explanation, and perhaps this is the best explanation.
Some places I have read that the name Mallory/Mallorie can mean "beautiful" in French. I've tried to confirm this and have found nothing. In fact, here's a block of text translated with many words for physical attractiveness translated into French...nothing looks at all to be like Mal or Mallory.
belle attrayant beau beauté belle jolie mignonne adorable Devine ravissante belle angélique admarable séduisante appel charme magnifique sublime ravissante superbe merveilleux alléchantes alléchants beau teasing à couper le souffle incroyable magnifique agréable
Mallory can also mean "mail" as in the iron mail worn by knights. Perhaps there is something here, as Cobb perhaps may be using Mal to protect him from something else, or protect him from others invading his own mind (if you follow the complicated theory that Cobb is actually the one being incepted during this film).
If her name is Mallorie
If her name is Mallorie, then there are tons of popular choices to chose for her relations or namesake in fiction, history, and modern science-fiction and fantasy.
(Pictured right is one of many classic images from nineteenth century printing of Mallory's work, the art is done by Aubrey Beardsley).
Of course you may find this an ironic conclusion for me to make based on the fact I discount King Arthur as the inspiration behind Joseph Gordon-Levitt's character 'Arthur.' And honestly, I generally discount my own theory here as well based off the inclusion of the full name of Mallorie.
Other Possible References for Sci-Fi/Fantasy Fan
There are a few recent "Mal" characters who have shown up in science fiction/fantasy works that Christopher Nolan could have been playful hinting at. I don't know that this is the case, but I'll consider it.
One possibility is Malcolm Reynolds (Nathan Fillion) from the Firefly franchise. He goes by "Mal" in the franchise, and does act out of personal lost.
Another possibility is the Mallory from the show Sliders. In the final seasons of this sci-fi show there is one character who exist in two alternate realities. There is Quinn Malory as well as the fraternal alternate who typically just goes by the name "Mallory" and there is a great effort to combine these two alternate world characters into one person.
Frankly, it seems to me that Mal's character connected to some grander historical or fictional character while not only challenging, simply may not exist.
Instead I think it is important to ask the question "Is she evil?" because her name clearly presents that suggestion.
Personally, I like the idea that she was "Mallorie" [unfortunate] but upon her death, her role in her husband's subconscious has become "Mal" [evil].