Invisible Woman is the founding member of Fantastic Four, she received her powers during a space mission when their space ship was hit by a cosmic storm. She has the powers of invisibility which hides himself and invisible force field which help her to create an invisible protective invisible shied which protects from any sort of attacks. She is also a martial artist.Source here
image sourceInvisible's real name is Susan Storm and has a younger brother, Johnny Storm which also turned to be a super hero Human Torch and a member of Fantastic Four.She is also a good hand-to-hand combatant which has been trained by Iron Fist and also received additional coaching from both The Thing and She-hulk. She is a natural-born leader and acts a their team's second in command.Source here