Gabriel Gray, more commonly known by his assumed name of Sylar, is a fictional character, one of the primary antagonists, and, as of the third season, an anti-hero on the NBC drama Heroes. Portrayed by Zachary Quinto, he is a superpowered serial killer who targets other superhumans in order to steal their powers. While he served as the primary villain of the first season, he has since begun the road to redemption in Season 3.
It was recently revealed that he is the biological son of Angela and Arthur Petrelli, thus making him brother of Nathan and Peter Petrelli, as well as the uncle of Claire Bennet.
Nicole "Niki" Sanders is a fictional character portrayed by Ali Larter in the television series Heroes. Niki is the wife of D.L. Hawkins (Leonard Roberts) and mother of Micah Sanders (Noah Gray-Cabey). Niki, a sufferer of Dissociative Identity Disorder, displays superhuman strength, being able to literally rip others in half. Initially, she is only able to access this power when her alter ego "Jessica" is in control.
Tim Kring, the creator of the show, stated that he originally created Niki with the power to be in two places at once, which stems from her life as a single mother. Niki was also originally written to be a showgirl. However, Ali Larter did not have the proper physique to portray a showgirl, so the character's profession was changed to internet stripper. According to writers Joe Pokaski and Aron Coleite, Niki was written out of the series and replaced with Tracy so that Larter could play a different role, as they realized that they could not go further with the character. The change also allowed them to tell an origin story, where the character discovers that she has powers.
Micah Sanders, portrayed by Noah Gray-Cabey, is a fictional character on the NBC science fiction drama series Heroes. He is the son of Niki Sanders and D.L. Hawkins. He is a child prodigy and a technopath.
Peter Petrelli, portrayed by Milo Ventimiglia, is a fictional character on the NBC science fiction drama series Heroes. He is a former hospice nurse in his mid-20s formerly with the power to absorb and mimic the powers of other people with abilities. Sensitive and compassionate, the character was initially defined by his complex relationship with his older brother, Nathan. Since that time, Peter Petrelli had to deal with the possible outcomes that his abilities force him to make.
Nathan Petrelli, portrayed by Adrian Pasdar, is a fictional character on the NBC science fiction drama series Heroes. He is a New York lawyer-turned-senator with the power of self-propelled flight, the older brother of Peter Petrelli and Gabriel "Sylar" Gray, biological father of Claire Bennet, and son of Arthur and Angela Petrelli. Nathan, ambitious and pragmatic, has a decidedly anti-hero streak, which exacerbates his complex relationships with his brother, Peter, and his biological daughter, Claire, and sometimes his mother, Angela.
Matthew "Matt" Parkman is a fictional character of the NBC science fiction serial drama Heroes, played by Greg Grunberg. Matt is a police officer, who works for the LAPD and NYPD in Seasons One and Two respectively. He is a telepath; his ability allows him to read minds, and eventually extends into aspects of mind control. His ability attains to controlling all functions of the mind, as stated by Bob Bishop.
Hiro Nakamura (中村 ヒロ, Nakamura Hiro?) is a character on the NBC drama Heroes who possesses the ability of space-time manipulation, enabling him to teleport, alter the flow of time, and travel through time by bending the space-time continuum. He is played by actor Masi Oka.
According to the online comic on NBC.com, Hiro is named after Hiroshima, so that his family will always remember the atomic bombings of Hiroshima and Nagasaki. Tim Kring has been quoted as saying, "It's no coincidence we named him Hiro... he truly is on a hero's quest." To this end, his name is often used as a pun. His co-worker Ando once called him "Super-Hiro" in jest.
Adam Monroe, also known as Takezo Kensei (剣聖 武蔵, Kensei Takezō?) in feudal Japan, is a fictional character portrayed by David Anders in the NBC science fiction drama Heroes. The character first appears in the second season episode "Four Months Later...", although the legend of Kensei is referenced several times during the first season. His regenerative ability has halted his aging, making him over 350 years old in the present of the series. He is the primary antagonist during the second season.