Because demolisher is an occupation/class in the English world.
Still, I do not mind having both now since they are essentially the same root word with different suffix.
Demolisher sounds too “Street Fighter” to me… Demolitionist has more of an “Elizabethan” sound to me… so i voted Demolitionist.
And, as others have pointed out, Demolitionist is, indeed, a word.
Yes, at least 52 people clicked the wrong option. 
I don’t think this is much of an opinionas it is properly naming the class.
Demolisher sounds more like a title or nickname you give someone known for breaking things down
Demolisionist sounds like an actual preffesion, or class in this case
but, Demolisher is behind by quite a lot so… cool
(｀_´)ゞ
Yeah, me too. The demoli(whatever) / occultist hybrid should be called ‘Soulblaster’ 
Mastery: Demolitions
Class name: Demolitionist I guess…
Both names sound atrocious, but I probably won’t be inclined to ever pick the mastery, so it will go hand in hand with my play style.
what about “Devastator”
or perhaps Superbomberman 
How about this crazy super awesome suggestion of death and destruction:
Lord of Explosive Materials Causing Serious Bodily Harm
Lol…
Or Captain Kablooie.
Obviously just having fun here, at least these are possible character name haha.
What about “Sapper”?
From the Wikipedia entry for Sapper:
A sapper, also called pioneer or combat engineer, is a combatant or soldier who performs a variety of military engineering duties such as bridge-building, laying or clearing minefields, demolitions, field defences and general construction, as well as road and airfield construction and repair. They are also trained to serve as infantry personnel in defensive and offensive operations. A sapper’s duties are devoted to tasks involving facilitating movement of allied forces and impeding those of enemies.
Yea this has been brought up before and I think their is no definite answer as to what would be preferred.
I think everyone can be satisfied because, since this is like Titan’s Quest, their will be hybrid titles. So if Sapper isn’t the main mastery title, it could be one of the variants like Soldier+___ (Demolitionist or whatever it’s going to be).
Also people can create mods to change what they want so yea… options 
True, but there can be possible miscommunication if that was the case. One would be used to saying Demolisher and the other Demolitionist. Worst case can happen is that one would correct the other or vice versa (highly doubt it will happen, but eventually this forum will be less mature with more peeps joining in on the game). What was the point of the poll then, if you can easily mod the official class name? It would mean Crate was wrong for they did. Seems redundant to me.
Just trying to play Devil’s Advocate here.
Pyromaniac.
Demolitionist + Nightblade = Sapper
“A sapper, also called pioneer or combat engineer, is a combatant or soldier who performs a variety of military engineering duties such as bridge-building, laying or clearing minefields, demolitions, field defences and general construction, as well as road and airfield construction and repair. They are also trained to serve as infantry personnel in defensive and offensive operations. A sapper’s duties are devoted to tasks involving facilitating movement of allied forces and impeding those of enemies.”
My post is simply giving a possible example as nothing is set in stone.
We may or may not even see “sapper” in Grim Dawn.
After reading all these post all I can think about is Fiddler, who was a Sapper in the Malazan Empire series by Steven Erikson. Sappers played a big role in those books and aptly fit the description.
Demolitionist. Valve tried to name one of their Dota 2 characters “Outworld Demolisher” but changed it to “Outworld Devourer” because of public outcry. Unless the Demolisher can wear a construction hat.
I like Sapper.
The more I think on this, the more the term Sapper appeals to me. I mean, the term is easier off the tongue than Demolisher or Demolitionist, really only fits for a “pure demo” char (doesn’t really work as a dual class title IMO) and whenever I think Sapper, I think of words such as Grenadier and Siege Engineer, both of which Demolition mastery seems close to (one of its skills is a mortar, so siege engineer fits!)
Just my two cents,
Younghappy
Sapper, to me, will always be a goblin unit in the Warcraft series.