He is portrayed by Milo Ventimiglia.
Peter is the 'black/white sheep' of his family, being the only one who isn't a backstabber, manipulator, murderer or sociopath (his father is all four of these things). He is frequently at odds with his brother because of his idealistic views compared to Nathan's realistic views. He and Nathan are notably two of the only characters to appear as regulars in all four seasons, along with Claire Bennet, Noah Bennet, Hiro Nakamura, Matt Parkman, and Mohinder Suresh.
Peter's original ability is to mimic the powers of others, acquiring powers simply by being near someone. Peter is eventually stripped of his abilities by his father Arthur Petrelli, before later regaining a modified form of this ability called ability replication through the formula.
Series creator Tim Kring stated that Peter's original ability is "based on his empathy and his ability to connect with people." As well, Claude refers to Peter as empathic. According to Dr. Suresh, Peter's DNA automatically resequences itself to mimic the abilities of those around him. At first, Peter could only mimic powers while in close proximity to their source, but then learned how to recall previously mimicked powers with greater and greater ease with the help of Claude. Angela Petrelli describes Peter as being "the most powerful of us all".
He has acquired the powers of invisibility, telekinesis, space-time manipulation, rapid cellular regeneration, flight, superhuman strength, radioactivity, intangibility, electrokinesis, precognition, telepathy, pyrokinesis, intuitive comprehension and super speed.
During a confrontation with his father in "Dying of the Light", Peter is stripped of his empathic mimicry as well as every ability he had previously absorbed.
In the mid-season finale, "Dual", he injects himself with a power granting formula and gains a new, more limited mimicry ability called ability replication. He is once again able to mimic others' powers, but now he requires physical contact to do so, and can only retain one ability at a time, losing the previous power each time he gains a new one. Heroes producers Joe Pokaski and Aron Coliete said in an interview that, "Peter is still trying to get a handle on his powers. Just like during the first season, it’s going to take him some time to get a handle on these powers." By the time of the episode "Cold Wars", he has gained enough control over his mimicry that he can touch people without taking on their powers if he wants to.