Invisible Woman

Origins  

Susan Storm, and her younger brother, Johnny, lived their early lives in Glenville, Long Island. They were the children of Dr. Franklin Storm, a star surgeon, and his wife, Mary. Their peaceful lives fell apart upon the death of Mary Storm in an automobile accident. Dr. Storm failed to save his wife, and suffered immeasurable guilt as a result. He gave up his career and descended into gambling and drinking. He eventually winded up in prison, charged with manslaughter. 
 
The loss of both parents lead Sue to become more responsible and mature, and she started taking a more active role in raising Johnny. The siblings eventually went on to live with their aunt, Marygay, where Sue promptly developed a crush on Reed Richards, her aunt's boarder. Sue decided to move to California for college. It was here that she met Richards again, and the two soon became engaged.
 
Like the rest of the founding members of the Fantastic Four, Sue chose to accompany Reed Richards on the test flight of an advanced spaceship the latter was building for his journey to Mars and beyond. The flight was a desperate attempt on the part of Richards to see his project through before the government cut his funding. In space, the group was exposed to heavy amounts of cosmic radiation during their passage through the Van Allen belt. The ship's insufficient shielding forced the heroes to return to Earth immediately. Upon crash landing they discovered that their bodies had been mutated by the cosmic radiation and that they had gained superhuman abilities. Susan discovered that she could now manipulate light waves, giving her the ability to render herself invisible. 
 
As a member of the newly formed Fantastic Four, Susan went on to adopt the alias "Invisible Girl".                                                        
    

Role in  the Fantastic Four

 In the group's earlier adventures, the limited offensive capabilities of her initial range of powers led Sue to frequently be used as a sort of damsel-in-distress. However, this changed with the discovery of her new, more offensively capable abilities, and she assumed a much more prominent role in the team's adventures. This growth in her powers was matched by a growing sense of confidence and the development of her leadership abilities. She soon became the second-in-command of the Fantastic Four. 
 
Sue is now regarded as one of Marvel's premiere superheroines.
 

Powers                                 

Due to her ability to bend and manipulate light waves, Sue can render herself (and others) invisible at will. She retains her vision while invisible by using her powers to direct light into her eyes.  
 
This was, initially, the full extent of Sue's powers, and lead her to assume a more passive role in the group's adventures. Before long, however, Sue discovered her ability to generate near-indestructible force fields around herself and others. These force fields are completely invisible, and Sue appears to have some amount of control over their density and strength. She can also alter the shape and size of these force fields at will, allowing her to create invisible constructs and use them as weapons. By manipulating energy she can achieve a facsimile of telekinesis. 
 
Susan is also trained in hand-to-hand combat, though her physical strength itself is not superhuman. 
 

Limitations

Susan can only turn up to 1,133 cubic meters of volume invisible at a single time. The largest force construct she can create and sustain at a single time is 30 meters in diameter. However, this limitation only applies if the construct in question is solid and not not hollow. 
 
While Susan's control over her powers is entirely mental, their extensive application seems to affect (and be affected by) her physical condition at the time: powerful attacks on her force fields have been known to cause her physical pain.