boo-yah

[republickin]

According to an interview with Heroes writer Bryan Fuller, one explanation was considered, though avoided. "[Sylar] kills people and eats their brains and [...] digests their powers," but this wasn't stated in the series because it seemed "silly" and zombie-like. Mr. Bennet confirms that Sylar has gained multiple powers in this manner, but the full extent of his abilities remains unknown.
(taken from the Heroes wiki)