Samson Gray is Sylar's biological father. He is a evolved human dying of cancer, assumedly lung cancer due to him being seen smoking.
He sees himself as a predator, and those he kills and replicates their powers, prey. His hunter beliefs is also noted when Samson stated that Sylar was hunting "small game" as those Sylar killed were absolutely no match to someone with such power. After his battle with his son (over the power of rapid cellular regeneration) he was spared by Sylar, who deemed that his father didn't deserve such an ability as he didn't have the power to take it.
Samson Gray's original ability was that of perceptive comprehension. Also known as Intuitive Aptitude he used this power to learn how other evolved humans used their powers and replicate them. This power may be genetic as it was passed down to his son Gabriel "Sylar" Gray. The following powers are the abilities we've seen Samson use after replicating them. However, it can be assumed he has many more powers as he was heard saying "I have several [abilities]."