• The original version of September seen in the pilot and introduced in 'The Arrival'.
• He could be considered the catalyst for everything that happened in Fringe due to his distraction of Walternate in 1985.

• List of appearances  
Season 1
• S1E01 - Pilot
• S1E02 - The Same Old Story
• S1E03 - The Ghost Network
• S1E04 - The Arrival
• S1E05 - Power Hungry
• S1E06 - The Cure
• S1E07 - In Which We Meet Mr. Jones
• S1E08 - The Equation
• S1E09 - The Dreamscape
• S1E10 - Safe
• S1E11 - Bound
• S1E12 - The No-Brainer
• S1E13 - The Transformation
• S1E14 - Ability
• S1E15 - Inner Child
• S1E16 - Unleashed
• S1E17 - Bad Dreams
• S1E18 - Midnight
• S1E19 - The Road Not Taken
• S1E20 - There's More Than One of Everything
• Bonus - Unearthed

Season 2
• S2E01 - A New Day in the Old Town
• S2E02 - Night of Desirable Objects
• S2E03 - Fracture
• S2E04 - Momentum Deferred
• S2E05 - Dream Logic
• S2E06 - Earthling
• S2E07 - Of Human Action
• S2E08 - August
• S2E09 - Snakehead
• S2E10 - Grey Matters
• S2E11 - Johari Window
• S2E12 - What Lies Below
• S2E13 - The Bishop Revival
• S2E14 - Jacksonville
• S2E15 - Peter
• S2E16 - Olivia. In the Lab. With the Revolver.
• S2E17 - White Tulip
• S2E18 - The Man from the Other Side
• S2E19 - Brown Betty
• S2E20 - Northwest Passage
• S2E21 - Over There (Part 1)
• S2E22 - Over There (Part 2)

Season 3
• S3E01 - Olivia
• S3E02 - The Box
• S3E03 - The Plateau
• S3E04 - Do Shapeshifters Dream of Electric Sheep?
• S3E05 - Amber 31422
• S3E06 - 6955 kHz
• S3E07 - The Abducted
• S3E08 - Entrada
• S3E09 - Marionette
• S3E10 - The Firefly
• S3E11 - Reciprocity
• S3E12 - Concentrate and Ask Again
• S3E13 - Immortality
• S3E14 - 6B
• S3E15 - Subject 13
• S3E16 - Os
• S3E17 - Stowaway
• S3E18 - Bloodline
• S3E19 - Lysergic Acid Diethylamide
• S3E20 - 6:02 AM EST
• S3E21 - The Last Sam Weiss
• S3E22 - The Day We Died

Season 4
• S4E01 - Neither Here Nor There
• S4E08 - Back to Where You've Never Been
• S4E14 - The End of All Things
• S4E15 - A Short Story About Love
• S4E22 - Brave New World (Part 2)