Found this list of bosses over at
Guild Hall. I don't know if its comprehensive--but its a damn good list none the less!
Bija Gravewailer - lvl 17 skeleton mesmer boss using ether feast, located in a swamp area with a bridge
Najja Doombringer - lvl 17 skeleton elementalist boss in the same area
Wydd Kindlerun - lvl 19 wind rider type boss down in a shallow river
Rawr Wildeye - lvl 15 necro boss using Mark of Subversion, looks like a tengu, seems to be the explorable area with captain greywind
Nizza the Sickle - lvl 17 eexecutioner boss
Bane Darkfist - lvl 17 necro skeleton boss using Life Syphon and death nova in the mission with confessor Dorian
Raja Crux - lvl 17 skeleton boss with a big tall red gem in his hat in a swampy area with a bridge
Zameel Dirge - lvl 17 executioner warrior boss using brutal blow in an area with Justiciar Hablion
Hepp Bilespitter - lvl 20 mesmer wind rider boss, can't see much more than a green grassy ground and green walls
Mossk Rottail - lvl 20 scorpion boss, seems to be glowing green, in a jungle area
Nyle the Compassionate - lvl 20 mesmer human-looking boss in a jungle area
Lars the Obeisant - lvl 20 mesmer human-looking boss using guilt, jungle looking area
Holt the Iron Boot Heel - lvl 20 warrior white mantle looking boss, uses executioner's strike, in a jungle/desert looking area
Kenric the Believer - lvl 20 red and glowing green human-looking boss in a jungle area
Henge Guardian - lvl 20 boss (one of those snake stuck in the ground monsters that I can't remember the name of) at the end of one of the missions, the one right before Denravi I think
Damis the Malignant - lvl 20 undead horserider necro boss
Gren Wavelslosh - lvl 17 mesmer gargoyle boss using ether feast in a beach area
Bearn the Implacable - lvl 20 necro boss using order of pain, seems to be in what was called "mission 6"
Dracul Cadava - lvl 21 boss using reversal of fortune in a grassy area
Ruinwing - lvl 21 bone dragon boss in the same area
Gaiza Deadeye - lvl 21 mesmer boss, looks sort of like a small undead rift warden, seems to be in the same/similar area as the last 2
Cyrus the Unflattering - lvl 20 white mantle boss of "mission 6"
Darwym the Spiteful - lvl 20 ranger boss on a big brige in an exporable area
Dread Nightstalk - lvl 24 pitch black and glowing green animal boss of some sort in the same exporable area
Rawr Wildeye - lvl 15 necro tengu boss using Suffering, who I think was in the same area as captain greywind
Pello Agileclaw - lvl 15 tengu boss in the same area
Corbin the Upright - lvl 20 monk boss using divine intervention and Judge's Insight in a beach/jungle type area
Bearn the Implacable - lvl 20 necro boss using Verata's Gaze, seems to be in an explorable area, not the same place as the other Bearn
Scale Fleshrend - lvl 24 glowing red drake boss in the same area as the last 2
Manton the Indulgent - lvl 20 white mantle boss using Ward against Elements in a dry/desert looking area
Kenric the Believer - lvl 20 necro human-looking boss using mark of subversion in the same area
Kemal the Deadened - lvl 17 blue glowing undead skeleton boss attacking a townsperson, in the mission with Confessor Dorian
Ziyad Soulreaper - lvl 17 mesmer boss in the same area
Abijah the Decayed - lvl 17 ranger boss in the same area using tongue biter
Grech Trundle - lvl 19 necro boss in jungle looking area using deathly swarm
Paka Blackhoof - lvl 19 boss in same area
Rapa Ironhaunch - lvl 19 warrior minotaur boss in same area
Smuush Fatfist - lvl 15 ettin boss in snow area (Gryphon's Mouth I think) using brutal blow
Braiama the Callous - lvl 20 white mantle boss in one of the later missions
Zeki Lament - lvl 21 mini rift warden looking boss using conjure lightning in same area
Essam Festerskull - lvl 21 executioner warrior boss in same area
The Judge - lvl 15 stone boss using water attunement in a partly snowy area between Lion's Arch and Ascalon
Cruc the Reborn - boss in a huge pack outside Ascalon
Lumps Ruinator - another boss in that pack (one is glowing purple and one yellow, I can't tell which is which)
Maim Deathrain - lvl 7 ranger charr boss using favorable winds in same area
Igmon Quivcaver - lvl 10 mesmer stone boss in same area
Mirash Dreambreaker - lvl 5 charr mesmer boss using illusion of haste and energy burn outside of ascalon
Igg Fecpelter - lvl 5 green glowing boss in one of the first missions
Claw Fleshfixer - lvl 5 gargoyle boss using whirlwind and lightning orb in the same mission
Slur Scarchest - lvl 5 ranger charr boss using troll unguent in the same mission
Vatlaaw Doomtooth - glowing green charr boss in an ascalon looking area
Rrrack Whitefire - lvl 5 mesmer boss using bane signet in an ascalon looking area
Fling Bloodpelt - lvl 7 ranger charr boss using troll unguent in one of the first missions
Puugh the Slasher - lvl 7 warrior boss using cyclone axe in the mission with Prince Rurik
Ignis Phanaura - lvl 7 boss in Ruins of Diessa
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