One Observer repeatedly appears at, or near, the scene of cases associated with the Fringe Division task force and Dunham's science team. His brief, succinct, and mysterious conversations, particularly with Walter, carry significant gravitas and imply great importance as to what he is sharing.
The ominous nature of the Observers makes them significant to the overall story-arc. Their appearance varies only slightly between suit, tie and hat. Modest, dark sunglasses are commonly donned. Their general demeanor is calm and collected. One of the Observers, August, who may have been in 'love' - shed a tear, suggesting that the Observers are capable of emotion. However, the discourse between two Observers suggests that they are unfamiliar with emotions, suggesting that, while they are capable of it, they are devoid of it. They possess the ability to read minds, the technology to view future events and to travel through time.
A group of at least ten Observers stand outside of the Statue of Liberty on Liberty Island, in this universe, after Peter vanished from the timeline. (The Day We Died)
In Letters Of Transit, one Observer causes a native to bleed from the ears while attempting to wipe his mind. Walter shares that September told him the Observers are from 2609.
 Known Observers
- The Observer, known for his mission around the Bishops' and Olivia. Seriously wounded (Back To Where You've Never Been) with what appears to be a gunshot to the chest.
- August, who fell in love with Christine Hollis and may have died as a result.
- December, who appears to lend some level of supervision to the others.
- July, whose activity has been to report August's misconduct.
- March, who recovered the time-viewing device lost at Reiden Lake.
- Captain Windmark, manages the occupying force in the north eastern US in 2036.
- The Commander, Windmark's superior who wants to study the Anomaly XB-6783746.
- The Child, who was bald displayed empathic abilities in Inner Child. His transportation to a safe location was also witnessed by the Observer. The tunnel the Child was found in had been sealed for at least seventy years. He was created in a lab with genetic material of another Observer (September). His brain developed differently and his maturation was stopped because he was a defect. He was labelled as Anomaly XB-6783746. He was scheduled to be destroyed but September hid him.
 Historical Appearances
According to the episode August, The Observers (though it is not made clear which observer specifically) have been spotted at various important events throughout history evidenced by his appearance in notable historical paintings and images.
- An Observer is present as an onlooker in the crowd depicted in the painting "The Bloody Massacre" which depicts the Boston Massacre of 1770.
- An Observer is present, again as an onlooker in a crowd in a painting of Marie Antoinette being taken for execution during the French Revolution
- An Observer is present in a photograph of Archduke Franz Ferdinand and his wife leaving a building moments before their assassination which served as the catalyst for World War I.
|— Plot Relevant Questions —||Address theories about questions on Observers/Theories Ask minor questions on the Talk Page|
1) Do not answer the questions here.
- What is the relationship, or difference, between the time travelling Observers and the bald men occupying Manhattan in 2036 (Letters Of Transit)?
- Are Observers affected by the ultrasonic energy emitted by the box (The Box)?
- If not, why?
- Why do Observers take so much interest in the Fringe Divisions, and their cases, in both universes?
- What do the Observers hope to gain by taking control of the timeline in 2015?