The following NPCs can be found in Zangarmarsh.
Questgivers[]
Alliance[]

Anchorite Ahuurn
[10-30] The Orebor Harborage
[10-30] The Boha'mu Ruins
[10-30] Idols of the Feralfen
[10-30] Gathering the Reagents
[10-30] Messenger to the Feralfen

Haalrun <Alchemy Supplies>
[10-30] Too Many Mouths to Feed
[10-30] Diaphanous Wings

Ikuti <Kurenai>
[15-30] Concerns About Tuurem
[10-30] Daggerfen Deviance
[10-30] Ango'rosh Encroachment
[10-30] Overlord Gorefist
[15-30] A Message to Telaar

K. Lee Smallfry <Grand Master Engineer>
[10-30] The Zapthrottle Mote Extractor! (Engineering)

Maktu <Armor Merchant>
[10-30] Natural Armor
[10-30] Maktu's Revenge

Puluu
[10-30] Stinger Venom
[10-30] Lines of Communication
[10-30] The Terror of Marshlight Lake

Noraani <Reagent Merchant>
[10-30] Menacing Marshfangs
[10-30] Umbrafen Eel Filets

Prospector Conall <Explorers' League>
[10-30] Unfinished Business
[10-30] Blacksting's Bane

Ruam
[10-30] Fulgor Spores
[10-30] Withered Flesh
[Strange Engine Part]
[10-30] Strange Engine Part

Timothy Daniels <The Specialist>
[10-30] Secrets of the Daggerfen
[20-30] No Time for Curiosity

Vindicator Idaar
[15-30] The Fate of Tuurem
[10-30] The Dead Mire
[10-30] An Unnatural Drought

Wanted Poster (Orebor Harborage)
[10-30G] WANTED: Chieftain Mummaki
Horde[]

Gambarinka <Tradesman>
[10-30] The Sharpest Blades
[10-30] Stinging the Stingers

Mack Diver <Grand Master Engineer>
[10-30] The Zapthrottle Mote Extractor! (Engineering)

Magasha
[10-30] No More Mushrooms!
[10-30] There's No Explanation for Fashion
[10-30] A Job Undone

Messenger Gazgrigg
[15-30] Reinforcements for Garadar

Reavij
[10-30] Menacing Marshfangs
[10-30] The Respect of Another

Seer Janidi <Reagent Vendor>
[10-30] Spirits of the Feralfen
[10-30] A Spirit Ally?

Shadow Hunter Denjai
[10-30] Impending Attack
[10-30] Message to the Daggerfen
[10-30] Us or Them
[20-30] The Ogre Threat

Wanted Poster (Zabra'jin)
[10-30] WANTED: Boss Grog'ak

Wanted Poster (Zabra'jin)
[10-30G] WANTED: Chieftain Mummaki

Witch Doctor Tor'gash
[10-30] Burstcap Mushrooms, Mon!
[10-30] Have You Ever Seen One of These?

Zurai <Merchant>
[15-30] News from Zangarmarsh
[10-30] Report to Shadow Hunter Denjai
[10-30] Thick Hydra Scales
[10-30] Searching for Scout Jyoba

Zurjaya <Fishing Trainer>
[10-30] Angling to Beat the Competition
[10-30] Pursuing Terrorclaw
[10-30] The Biggest of Them All
Neutral[]
["Count" Ungula's Mandible]
[10-30] The Count of the Marshes
[Drain Schematics]
[10-30] Drain Schematics

Fahssn <Sporeggar>
[10-30] The Sporelings' Plight
[10-30] More Spore Sacs (Repeatable)
[10-30] Natural Enemies
[10-30] More Tendrils! (Repeatable)
[10-30] Sporeggar

Gshaff
[10-30] Fertile Spores
[10-30] More Fertile Spores (Repeatable)

Gzhun'tt
[10-30] Now That We're Friends...
[10-30] Now That We're Still Friends... (Repeatable)
[10-30D] Bring Me A Shrubbery! (Dungeon)
[10-30D] Bring Me Another Shrubbery! (Dungeon, Repeatable)

Ikeyen
[10-30] The Umbrafen Tribe
[10-30] A Damp, Dark Place

Kayra Longmane
[10-30] Escape from Umbrafen

Khn'nix
[65D] Stalk the Stalker (Dungeon)

Lauranna Thar'well <Expedition Cataloguer>
[10-30] Saving the Sporeloks
[10-30] Plants of Zangarmarsh
[10-30] Identify Plant Parts (Repeatable)
[70D] Master of Potions (Alchemy)

Lethyn Moonfire
[10-30G] The Dying Balance (Group)
[10-30] Watcher Leesa'oh
[15-30] What's Wrong at Cenarion Thicket?

Msshi'fn <Sporeggar Primus>
[10-30] Glowcap Mushrooms
[10-30] More Glowcaps (Repeatable)

T'shu
[65D] Oh, It's On! (Dungeon)
[Uncatalogued Species]
[10-30] Uncatalogued Species

Wanted Poster (Cenarion Refuge)
[10-30] Leader of the Bloodscale
[10-30] Leader of the Darkcrest

Warden Hamoot
[10-30] A Warm Welcome

Watcher Jhang
[10-30D] Lost in Action (Dungeon)
[70D] The Warlord's Hideout (Dungeon)

Watcher Leesa'oh
[10-30] Observing the Sporelings
[10-30] A Question of Gluttony
[10-30] Familiar Fungi
[10-30] Stealing Back the Mushrooms

Windcaller Blackhoof
[10-30G] Safeguarding the Watchers (Group)
[10-30] Blessings of the Ancients
[Withered Basidium]
[10-30] Withered Basidium

Ysiel Windsinger <Expedition Leader>
[10-30] Disturbance at Umbrafen Lake
[10-30] As the Crow Flies
[10-30] Balance Must Be Preserved
[10-30] Warning the Cenarion Circle
[10-30] Warden Hamoot
[65] Failed Incursion
[70D] Preparing for War (Dungeon)
[70] Coilfang Armaments (Dungeon, Repeatable)
Class Trainers[]
None
Profession (Tradeskill) Trainers[]
Alliance[]

K. Lee Smallfry <Engineering Trainer>
Horde[]

Zurjaya <Fishing Trainer>
Mack Diver <Engineering Trainer>
Neutral[]

Juno Dufrain <Fishing Trainer>
Naka <Cooking Trainer>
Merchants[]
Alliance[]

Alliance Field Scout (PvP rewards)
Caregiver Abidaar <Innkeeper>
Doba <Cooking Supplies>
Haalrun <Alchemy Supplies>
Innkeeper Kerp <Innkeeper>
Loolruna <Armorer>
Maktu <Armor Merchant>
Muheru the Weaver <Tailoring Supplies>
Noraani <Reagent Merchant>
Puluu (Trade Goods)
Timothy Daniels <The Specialist>
Horde[]

Captured Gnome <Item Repair>
Gambarinka <Tradesman>
Horde Field Scout (PvP rewards)
Lorti <Merchant>
Merajit <Innkeeper>
Seer Janidi <Reagent Vendor>
Zurai <Merchant>
Zurjaya <Fishing Trainer>
Neutral[]

Fedryen Swiftspear <Cenarion Expedition Quartermaster>
Innkeeper Coryth Stoktron <Innkeeper>
Juno Dufrain <Fishing Supplies>
Mortog Steamhead (Requires Cenarion Expedition: Exalted)
Mycah <Sporeggar Quartermaster>
Naka <Cooking Supplier>
Sarinei Whitestar <General Goods>
Various Services[]
Alliance[]

Caregiver Abidaar <Innkeeper>
Halu <Hippogryph Master>
Innkeeper Kerp <Innkeeper>
Joraal <Stable Master>
Munci <Hippogryph Master>
Horde[]
Neutral[]

Innkeeper Coryth Stoktron <Innkeeper>
Kameel Longstride <Stable Master>
Other Notable NPCs[]
Alliance[]
Horde[]

Farbosi
Gargle <Tor'gash's Pet>
Guard Untula
Gurgle <Tor'gash's Pet>
Tayemba
Neutral[]

Ashyen <Ancient of Lore>
Buddy
Corvax
Hch'uu
Keleth <Ancient of War>
Morthis Whisperwing <Druid of the Talon>
Rook
Talut
Hostile[]

Blacksting
Bog Lurker (Rare)
Boglash (Elite)
Boss Grog'ak
Captain Bo'kar
Captain Krosh
Chieftain Mummaki
Coilfang Emissary (Rare)
"Count" Ungula
Kataru
Lord Klaq
Mal'druk the Soulrender (Elite)
Marsh Baron Brok
Marticar (Rare)
Mragesh
Overlord Gorefist
Rajah Haghazed (Elite)
Rajis Fyashe (Elite)
Ssslith (Elite)
Terrorclaw