My comic has a fixed ending, but I've left it open enough to change it in the future if I want to.
I could change my mind and continue the story though: I wrote it that way for that reason.
I know exactly how I want mine to end, for me I need to know that in advance before I work on the story so I know what I'm going towards.
More or less, I often go with the flow and since I started my comic many things changed but they are all going in the direction that I planned. But it's more of a open thing, it's nice when you can adjust the ending to make it better!
I know exactly how I want Enchiridion to end. The only problem is getting there. I've basically only have the first 3 chapter thought out and then some of the bigger events with no idea how to get to them. That said the ending isn't permanent if I come up with a better one I'll change it. It's my make it up as I go series.
And Rebuild is going to be oneshot with an ending that implies that it can be turned into a series (but probably won't). I haven't completely thought out but a lot of the things are difficult for me to draw so I'm struggling.
I wouldn't want to start a comic without a conclusion in mind - I did that as a highschooler and became trapped in that comic (and seeing other artists get caught in a redrawing loop as they improved their skills over years but became dissatisfied with their first pages made me want reconsider).
I'm currently posting a stand-alone episodes comic, which I feel freedom from.
Over years I have been working on several comics of various length but never started seriously drawing them until I knew where it was heading (I actually almost always start writing from the ending 
).
Recently, I have been thinking of seriously drawing a comic that has a proper ending but in those 150 or so pages I can't explore the whole world and explain everything, so I think that if the story were to become popular, I would make a sequel where the rest is explained.
I find it really important to have a clear ending in mind.
Well, i have to admit, I do have an ending, but it's very very vague! Haha. I don't plan for my story to be very long and for some reason, it's just easier for me to see the end without the details. I'm only about a chapter ahead in writing and I really need to step it up!
Already plan it. It's going to be EPIC with everything concluded and revelation will be out and epic stuff will happen...
And i need a hella lot skill's to pull it off... fortunately it's still a LONG way to go so hopefully I can manage to improve
myself along the way... hopefully.
@ghostnxs how about you?
haha, nope that's why I'm starting to write short stories/ one shots so I can practice writing and finishing(I have a problem not doing that).
I have it very clearly written down how my current ongoing story should end. The ending changed a few times over the last few years, but it became obvious after a while. I find it extremely hard to start drawing a story without working out a conclusion first during the writing process.
I'd normally just wing it but I bet that would be a bad idea, especially for a long story. I get bored of long planning.
Oh yes, I have a solid idea how I want my story to end. And even if I make some changes to the meat of the plot, I still know the direction I need to go.
I have two similar endings I need to choose from for my horror comic... I need to fully write it out in script form as well.
It usually is beneficial to think of an ending as you're creating the beginning, so I did that with my newest comic too.
Main ending, yep!
Endings between chapters/arcs....much harder for me.
My writer: "I know you want X to happen in Y chapter, but what are you looking for as the ending to Y and Z chapters?"
Me: ╮ (. ❛ ᴗ ❛.) ╭
I have the preferred ending that I would ideally like to reach, and I have the emergency ending for if my health gets too poor and I need to stop drawing comics.
Hopefully I never have to use the emergency ending.
I know how Grassblades ends. I haven't worked out 100% of the details yet (there's a certain character who I haven't decided if they survive or not, and I don't know whether I'll end it right after the climax, or whether I'm adding an epilogue), but I know where I'm headed.
Being a sprawling, very long story-format comic, Grassblades needs to have a bit of structure to it; if I was just winging it, I'd write myself into a corner. There's going to be lots of stuff going on further down the line, and I need to know where everything is going so that all the separate characters and subplots keep heading in the same direction.
I have the whole story planned out!
Not that it matters, because at the rate I'm doing it, I'll probably die before I finish it. 
With the future series ideas I've come up with, I generally have the beginning and the end realized. Then as I begin to work on it, I do my best to have my characters get to that end, even if it takes forever. Kinda like the One Piece. We know Luffy's gonna get it at SOME POINT, (it's in the freaking title for crying out loud) but 70+ volumes in between? Is it ever gonna happen? Do we even want it to happen? Yes, but the journey is just so darn fun, it'll be sad to see it all end.