Klaw is a character in the Marvel Comics universe
. He first appeared in Fantastic Four
Ulysses Klaw was a physicist who created a device which turned sound waves into physical mass. However, this device needed vibranium to power it. As vibranium is found almost exclusively in Wakanda, Klaw knew that was where he needed to go. So Klaw headed up a team of mercenaries to steal as much vibranium as they could. While on his little "expedition" he killed the ruler of Wakanda, T'Chaka, in front of his son T'Challa's eyes. (T'Challa later became the Black Panther.) In retaliation, T'Challa used Klaw's sound blaster against him, blowing off Klaw's hand. Klaw and his mercenaries fled. Soon thereafter, Klaw returned for revenge with a sonic blaster in place of his hand. He was beaten by the Black Panther and the Fantastic Four.
Now, he was really miffed, so he decided to jump into his sound converter in hopes of gaining superhuman powers. Comic book physics being what they are, it worked, and Klaw was transformed into a being of sentient sound. This means that he does not need to eat, sleep, breathe, etc. He cannot be destroyed (conservation of energy and all that); however, he cannot exist in a vacuum because sound needs a medium to travel through. He can be struck, because he is quasi-solid, but no permanent damage can really come to him. If he is dispersed, he merely reforms, although this process can take months. He still wears his sonic "claw", which converts ambient sound energy into high-energy sound waves, concussive force, or sound constructs. Exposure to vibranium can destabilize his form, which generally reverts to sound energy that gets absorbed by his claw.
He has a real mad-on for the Black Panther, whom he is obsessed with destroying. He's also fairly unhappy with Songbird of the Thunderbolts since she used his sound technology for her costume. Since he can't die, it's likely that you'll see him in a comic again soon.