||played The Observer in Fringe
The identity and true nature of the man referred to as "The Observer" is not known. His presence has been documented at the scene of numerous Fringe phenomena, but he observes rather than acts. He writes down all of his observations in a black notebook. He also has a fondness for spicy food, and drinks plain water. He appears to share a telepathic bond with a young proto-Observer (in "Inner Child"), but the origins of his own abilities, if any, are not known. He and Walter Bishop are on speaking terms, and Walter appears to know who and what he is. He may or may not be gathering information for the alternate universe: a courier turns over gathered information on this reality to the Observer, or someone looking like the Observer, for delivery to "the enemy" in "Fracture."
In later episodes it is revealed that his name is September, and that he and his kind come from a distant and potentially alternate future in which Earth has been severely contaminated. Most Observers remain neutral, but September has taken an interest in the Bishop family and has aided them on several occasions, starting with rescuing Peter Bishop from drowning as a young boy.
All Observers exist in "hyper-attenuated time" through the use of technology, and can move fast enough to catch normal bullets. They can be contained by something known as a "stasis rune," but otherwise they can move so fast as to disappear. They also use an advanced pulsar pistol, and can travel through time.