Sylar (Gabriel Gray) is a fictional character and a primary antagonist of the NBC superhero drama series Heroes. Portrayed by Zachary Quinto, he is a super-powered serial killer who targets other superhumans in order to steal their powers. He served as the primary villain of the first season and then as a recurring antagonist. Over the course of seasons 2, 3 and 4, the writers depicted Sylar attempting at various times and under different circumstances to become a hero or curb his desire to kill, undergoing relapses at various stages. In the series' penultimate episode he experienced over three years of penitence in a mental prison, and later identifies himself as a hero in what became the show's series finale due to cancellation.

TV Guide included him in their 2013 list of "The 60 Nastiest Villains of All Time".

Sylar was created as a cannibal who ate his victims' brains and "digested their power"; in order to avoid the potential silliness and zombie associations, the producers deliberately made this fact vague in the series. In an interview with series creator Tim Kring, it is asked if Sylar eats brains, and he merely states "That's the popular speculation. There's a connection between the powers and the brain, and Sylar has found it." The question is addressed in the season three premiere, when he is depicted in the act of acquiring Claire Bennet's regenerative powers through examination of her brain with his hands. When Claire asks him the same question, he sounds surprised and replies "Eat your brain? Claire, that's disgusting." The writers never bridged the gap between the early insinuations regarding what Sylar does with the brains and the final incarnation they reveal in his encounter with Claire.

Prior to Quinto's first appearance in the episode "Seven Minutes to Midnight", the role of Sylar was played by stunt doubles, and usually, as in "One Giant Leap", the character's face being obscured by shadows. Quinto himself played the role with his face hidden in the same way until "Six Months Ago". In the second episode of the first season, "Don't Look Back", his voice is heard in a recorded phone conversation on Chandra Suresh's answering machine, spoken by voice actor Maurice LaMarche. Part of this conversation is heard again in "Six Months Ago", this time spoken by Quinto.

Sylar was raised as the son of a watchmaker, but was indoctrinated by his mother's repeated assertions to believe that he was special and deserved more in life. This and the "evolutionary imperative" to acquire new abilities are what drive him to kill the victims with powers. Taking the name "Sylar" from a watch brand, he has shed all connections to his former life as Gabriel Gray to the point where he angrily lashes out at anyone who calls him Gabriel.

In addition to the above, Sylar shows a marked lack of empathy. As seen in the episode ".07%", when shortly before killing Isaac Mendez, he casually comments on Mendez's lack of fear, with the sort of mild surprise that someone might express if he noticed that a train was running late.

Although he at times tries to impersonate other people in order to obtain a longer-term goal, Sylar is also unable to completely control his "hunger," or obsessive tendencies, to the extent that he still intimidates people when he is trying to gain their trust or co-operation. This was seen with Mohinder Suresh, when Sylar tried to impersonate Zane Taylor, and also with Claire Bennet's mother when Sylar was looking for Claire, as well.

Sylar's dominant trait was his innate desire to be recognized as special and admired. This was fueled by his mother's vocal disappointment in him for perceived failure and his own feelings that he did not get a chance to choose his destiny, being forced into the role of a watchmaker. He spent his life hoping to learn something extraordinary about himself.