Who/What is Sylar?

The baddest of the bad. The star villain of the show, Sylar's only appearance was as a teaser in 1 episode of Heroes so far, where Matt the mind-reading freak of a cop and his partner chase Sylar into a back hallway. It is seen in this scene that Sylar is one evil creature, able to make Matt's partner turn her gun on herself. Luckily, Matt intervenes in time to chase the villain off before he can finish the job. Matt also had a bar scene where he went unconscious. Did Sylar play into this event? Can Sylar change his appearance?

It makes you wonder if Sylar was created or came about like the rest of the heroes? He seems to have more and greater powers than the heroes, he can not only manipulate minds but it appears he can freeze his victims to death, similar to Silver Surfer of Marvel fame. On that note, I wonder what Stan Lee thinks of Heroes? It would be interesting to find out..

Another notion..Did all the Heroes have a terrible guilt hanging upon them when the eclipse occurred, and is guilt their one unifying trait that gave them each unique powers? Sure alot of people have guilt, but maybe these people were feeling it more than the rest of the world..