Adventure Time Story Writers

(Note 1: Adventure Time season 1 seems to have slightly different standards for who gets credited, and Pen, McHale, and Muto would've likely been credited as story writers for most of season 1 had they followed later season standards)
(Note 2: For the sake of this list, Season 5.1 is 22 episodes (Finn the Human to The Suitor as well as the aired out of order One Last Job), while season 5.2 is the remaining 30 (Party's Over to Billy's Bucket List). Meanwhile, Angel Face and President Porpoise is Missing fall before Stakes in production order)

>Pendleton Ward, Patrick McHale, and Adam Muto
The Enchiridion!

>other early Muto
Prisoners of Love (with early season 1 story editor Craig Lewis)
Evicted! (sole story writer)
Ricardio the Heart Guy (with Merriwether Williams and Tim McKeon)

>Merriwether Williams (story editor) and Tim McKeon (staff writer)
most of season 1

>Merriwether Williams (story editor), Steve Little (Staff Writer), Patrick McHale (Creative Director), Pendleton Ward (creator), and Thurop Van Orman (supervising producer)
most episodes in season 2 from the start to The Chamber of Frozen Blades (Her Parents in airing order)

>Mark Banker (story editor), Pat McHale, Pen Ward, and Van Orman
The Other Tarts

>Mark Banker, Merriwether Williams, Steve Little, Pat McHale, Pen Ward, and Van Orman
The Pods to Guardians in Sunshine (Merriwether absent in The Pods, Kent Osborne also involved in Guardians)

>Mark Banker, Pat McHale (switches to staff writer in season 3), Kent Osborne (also staff writer), and Pen Ward
post-Guardians season 2 and Season 3

>Kent Osborne (Head of Story), Pat McHale, and Pen Ward
season 4 and Season 5.1

>Kent Osborne, Pen Ward (not showrunner anymore but not still on the show), and Adam Muto (now Showrunner)
beginning of 5.2 to Be More (Muto absent from Be More)

>Kent Osborne, Jack Pendarvis (Story Editor), Pen Ward, and Adam Muto
post-Be More season 5.2, Season 6, pre-stakes Season 7, Stakes, and King's Ransom

>Kent Osborne, Jack Pendarvis, and Adam Muto
Season 7 (post-stakes, pre-Hall of Egress)

>Kent Osborne, Jack Pendarvis, Dylan Haggerty, and Adam Muto
Scamps
Don't Look
Daddy-Daughter Card Wars

>Kent Osborne, Jack Pendarvis, Ashley Burch, and Adam Muto
Hall of Egress to Orb (Muto absent from Hall of Egress and Flue Spell; Burch absent from Haggerty's episodes and The Music Hole; Kent absent from Do No Harm and High Strangeness)

>Kent Osborne, Jack Pendarvis, Julia Pott, and Adam Muto
Elements miniseries
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>>Other Story Writers (usually alongside the ones listed above)

>Post-Stakes Pendleton Ward
The Music Hole (episode was conceived all the way back in season 1)
Daddy-Daughter Card Wars
High Strangeness
Imaginary Resources

>post 5.1 Patrick McHale
Be More (had its origins in a scrapped season 3 episode)
The Music Hole (episode was conceived all the way back in season 1)
Cloudy (origins in an abandoned episode concept from way back in early season 1)

>Tom Herpich (regular writer/boarder)
Goliad
All Your Fault
Another Five More Short Graybles
Be More
Too Old
Dungeon Train
Apple Wedding
Lemonhope
The Tower
Ocarina
Dentist
Evergreen (sole story writer)
Walnuts & Rain
The Hall of Egress

>Jesse "Jmoyns" Moynihan (regular writer/boarder)
Sons of Mars
The Great Bird Man
The Suitor
Wizard's Only Fools
The Vault
Betty
Something Big
Astral Plane
The Mountain
Jermaine
You Forgot Your Floaties
Flute Spell
Normal Man

>Steve Wolfhard (regular boarder)
Another Five More Short Graybles
Be More
Dungeon Train
Apple Wedding
The Tower
Ocarina
Dentist
Graybles 1000+
Cherry Cream Soda (unusual in that he didn't board the ep)
The More You Moe, The Moe You Know

>Dick Grunert (production coordinator -> writer's apprentence; been on the show for its entire life)
Belly of the Beast
Web Weirdos

>Adam Muto
Reign of Gunters
Bad Little Boy

>Steve Little
The Suitor

>Doug TenNapel (boarder on the early scrapped episode The Glorriors)
Sons of Mars (apparently the episode borrowed some concepts from Glorriors)

>Andy Ristaino (lead model designer at the time)
Little Dude

>Rebecca Sugar (regular boarder)
Bad Little Boy
Be More (had its origins in a scrapped season 3 episode rebecca was boarding)

>Somvilay Xayaphone (regular boarder)
Chips and Ice Cream

>Seo Kim (regular boarder)
Chips and Ice Cream
Blank Eyed Girl

>Gilbert Hernandez
Mama Said

>Derek Kirk Kim (lead model designer at the time)
The Music Hole (which Kim had pitched all the way back in season 1)

>Guest Directors (sole story writer on their respective epsiode)
A Glitch is a Glitch (David OReilly)
Food Chain (Masaaki Yuasa)
Water Park Prank (David Ferguson)
Bad Jubies (Kirsten Lepore)