Observer Sightings are glimpses of an Observer in an episode. An Observer (usually September, but on rare occasions another Observer) appear in each and every episode. Sometimes they are easy to spot because they are the subject matter of an episode. Whether or not an episode revolves around a storyline pertaining to the Observers, however, an Observer can be seen in the background. Some are very easy to spot, while others are particularly challenging to find.

Picture Episode Description
Pilot September can be seen walking outside of Massive Dynamic.
The Same Old Story September can be seen at the hospital.
The Ghost Network September can be seen on the train.
The Arrival September is a part of this episode's storyline. As such, he is seen multiple times throughout this episode. He is tracking the arrival of The Beacon.
Images (1)
Power Hungry September can be seen exiting the elevator at the office building.
The Cure September can be seen at the fundraiser.
In Which We Meet Mr. Jones September can be seen at the airport.
The Equation September can be seen on the sidewalk.
The Dreamscape September can be seen in the Massive Dynamic hallway.
Safe September can be see on the computer screen showing security footage outside of the bank.
Bound September can be seen outside of Harvard University.
The No-Brainer September can be seen observing the car chase on the sidewalk.
The Transformation September can be seen on the soccer field.
Ability September can be seen on the sidewalk.
Inner Child September can be seen observing the child.
Unleashed September can be seen on the news.
Bad Dreams September can be seen on the street.
Midnight September can be seen in the club.
The Road Not Taken September meets Walter in the lab. He is central to the episode's storyline.
There's More Than One of Everything September guides Walter to the beach house. He is central to the episode's storyline.
Observer (3)
A New Day In The Old Town September crosses the blocked street in front of the empty vehicles from Olivia's crash.
Observer (4)
Night Of Desirable Objects September stands in the field near the Hughes' house, around the time Agent Jessop shows up to investigate.
Observer (5)
Fracture September receives and reviews photographs of Walter that were delivered by a secretive courier.
Observer (6)
Momentum Deferred September is seen observing Olivia and Charlie's conversation outside of Massive Dynamic Headquarters.
Observer (7)
Dream Logic September is seen walking down the stairs in Dr. Nayak's Clinic as Olivia is interviewing the nurse.
Observer (8)
Earthling September walks behind Broyles at the airport, while he is on the phone to Olivia.
Observer 207
Of Human Action September is seen observing the police car enter the multi-level parking structure.
Observer 208
August September is seen in company of other Observers and watching Olivia in an amusement park.
Observe 209
Snakehead September walks on Ping-On Street as the triad thug is called to follow Astrid to the lab.
Observer 210
Grey Matters September stands across the street as the tactical team attempts to locate Walter's tracking device.
Observer 211
Unearthed September walks behind Olivia as she talks to Maureen Donovan outside of St. Brigid's Church.
Observer 212
Johari Window September is seen standing in the background as the sheriff walks out of his office and the concerned locals from the town are gathered outside.
What Lies Below September walks behind CDC Field Director McFadden in the tent compound when Level-6 Eradication is being coordinated.
Observer 214
The Bishop Revival September walks past the window of the diner just before the attack there.
Observer 215
Jacksonville September walks in front of a large fire truck just as Broyles and the fringe team are arriving in front of the building from the alternate universe.
Observer 216
Peter September accidentally distracts Walternate from discovering a cure for the other Peter's illness (in the alternate universe) and subsequently must save Walter and the other Peter from drowning in Reiden Lake (in this universe).
Observer 217
Olivia. In the Lab. With the Revolver September crosses the street in front of Miranda Greene's car, just before she dies of cancerous tumours.
Observer 218
White Tulip September stands in a doorway near the accident that kills the time-travelling astrophysicist and his fiancée.
Observer 219
The Man from the Other Side September is standing in line at the bank when Thomas Newton walks up to the teller.
Observer 220
Brown Betty September is standing down the street from Walter's house as Walter comes home, concerned that Peter has not returned.
Observer 221
Northwest Passage September is standing behind the police tape with the crowd as Peter meets Sheriff Mathis.
Observer 222
Over There: Part 1 September passes behind Olivia in a bar and drops a file for her to read on the seat next to her.
Observer 223
Over There: Part 2 September passes behind Olivia, Walter and William Bell as they sit and talk at a fast food restaurant in the alternate universe.
Observer 301
Olivia September passes next to Henry's taxicab shortly after Olivia enters the park where she expected to find the parallel universe's version of Massive Dynamic
Observer 302
The Box September enters the subway station just as Thomas Newton abandons the box in order to visit the lavatory.
Observer 303
The Plateau September stands on the pedestrian overpass near Milo Stanfield as Milo throws a bicycle from it.
Observer 304
Do Shapeshifters Dream Of Electric Sheep? September transits the elevator lobby at Massive Dynamic while the Fringe team meets nearby.
Observer 305
Amber 31422 September lingers fifteen feet to the left of Olivia's parked vehicle when Agent Francis informs Colonel Broyles that her car is parked near the Riverdale Mutual quarantine site.
Observer 306
6955 kHz September stands with the crowd behind the crime scene tape after Peter discovers that the shapeshifter's dorsal memory chip is broken.
Observer 307
The Abducted September stands across the street from the diner as Olivia and Henry Higgins wait for breakfast and talk.
Observer 308
Entrada September stands outside of Penn Station, next to a taxicab, while Alt-Olivia Dunham meets a shapeshifter to receive harmonic implants
Observer 309
Marionette September stands across the street and reports on the Bishops as they enter Peggy's Malt Shop for a late night treat.
Observer 310
The Firefly September sets things in motion to prove to December that Walter has changed and would be willing to let Peter go when the time comes.
Observer 311
Reciprocity September stands behind the crowd at the Port Authority as disabled shapeshifter Michael Baird is extracted from the pond.
Observer 312
Concentrate and Ask Again September saunters into Congressman Thorn's gala fundraiser just before Olivia intercepts the final assassin.
Observer 313
Immortality September looks out the window at the Empire Docking Station while Alt-Olivia waits for Frank to return home.
Observer 314
6B September walks past Chris and Sylvia en route to the Kimball's party.
Observer 315
Subject 13 September walks into the lobby at Bishop Dynamic in the alternate universe, while Alt-Walter Bishop makes his way to his office.
Observer 316
Os September watches the crime scene with the gathered crowd outside the Metal Depository.
Observer 317
Stowaway September stands across the street from the science team as they begin to investigate Jim's suicide and Dana's survival.
Observer 318
Bloodline September watches Brandon intercept a blood sample in the hospital stairwell.
Observer 319
Lysergic Acid Diethylamide September strolls through the halls of the hospital after Bell/Olivia are wheeled in for treatment.
Observer 320
6:02 AM EST September walks behind Alt-Olivia and her nanny as they examine Alt-Olivia's child in a square.
Observer 321
The Last Sam Weiss September walks on the sidewalk behind Peter after his expensive taxicab ride to New York.
Observer 322
The Day We Died September stands with his colleagues on the grounds of Liberty Island in this universe after Secretary Bishop, Alt-Olivia Dunham and Brandon Fayette crossover from the alternate universe.
Observer 401
Neither Here Nor There September meets with his colleagues about the problem they created when they eliminated Peter from the timeline. He creates an electronic device from various components to influence Walter's memory. He is with a colleague near the crime scene following Danzig's murder.
Observer 402
One Night in October September enters the hospital recovery ward after Olivia chats with the disoriented Professor McClennan.
Observer 403
Alone in the World September walks in front of Walter's lab building as Olivia and Agent Lee begin to interview young Aaron Sneddon.
Observer 404
Subject 9 September loiters at Reiden Lake as Peter returns to the current timeline from the bottom of the lake.
Observer 405
Novation September waits behind the crime scene perimeter outside of Karen Truss' house when Olivia arrives to join Agent Lee.
Observer 406
And Those We've Left Behind September walks past the front entrance of Ann's apartment building in Central Village just a few moments before the flash-fire time anomaly reverts five year-old Samantha back into an infant.
Observer 407
Wallflower September stands in the crowd behind the police tape when Olivia tells Broyles that she and the canine unit failed to locate Eugene.
Observer 408
Back to Where You've Never Been September gives Olivia a message while she waits at the opera house. He disappears before Olivia can get him to a hospital to treat the bloody wound in his chest.
Observer 409
Enemy of My Enemy September does not appear in this episode. His colleague walks behind Agent Lee in the plaza as the crowd hurries to collect the money that Jones is distributing during his evasion.
Observer 410
Forced Perspective September does not appear in this episode. His colleague stands across the street from Olivia's Apartment while Nina tends to Olivia inside.
Observer 411
Making Angels September does not appear in this episode. His colleagues are covering his territory. They discover the device September lost at Reiden Lake, and was recovered by Neil Chung.
Observer 412
Welcome to Westfield September watches Atlantic Flight 591 crash with the stranded motorists near Westfield, Vermont.
Observer 413
A Better Human Being September walks past the cashier's window at the gas station when Peter enters, looking for Olivia.
Observer 414
The End of All Things September appears in Walter's lab and collapses from his injury. Peter establishes a synaptic link with him and learns about the role both of them play in the future of mankind.
Observer 415
A Short Story About Love September reappears to Peter after Peter activates the Beacon device he recovered with clues left for him.
Observer 416
Nothing As It Seems September walks along the sidewalk behind Peter and Lee as they arrive at the home of the transmogrified Daniel Hicks.
Observer 417
Everything In Its Right Place September watches Captain Lee escorting Canaan to the secure transport vehicle seconds before the sniper attacks them.
Observer 418
The Consultant September climbs the stairs behind Jones when Broyles meets him to take the device for Liberty Island.
Observer 419
Letters of Transit September is not seen in this episode but was referenced as providing key information to Walter when his society was attempting to purge this universe.
Observer 420
Worlds Apart September walks near Sally Clark on the shore of Sydney Harbour in New South Wales, one of Jones' planned seismic epicentres.
Observer 421
Brave New World: Part 1 September watches the emergency response outside of the Clane Centre from a semi-restricted view behind the ambulance.