A novel solution, however, I would like to post this reply as a thoughtful warning to anyone who has OCD and finds themselves in a similar situation.
Adding 1/2 drywall to what appears to be the offending wall surface in the above photograph will create a series of cascading effects that will ultimately further traumatize any potential OCD afflicted human.
1) The added drywall will wreck the reveal on the door/window trim farther down the hall. It will appear to be set into the wall deeper than any other window/door in the home.
2) You could take the trim off, drywall the offending wall, and put the trim back. But now the window/door casing is 1/2 too narrow, meaning you will have to...
a) Carefully manufacture a piece of material to bridge the gap. However, upon doing that, you now have one window/door casing that is different from all the others in the home.
b) Rip out the old door/window and buy one manufactured with a casing 1/2" wider and install it. However, you still have a window/door different from all the others in the home, presumably.
2) Surely there is some kind of mopboard or other trim along the floor. This will have to be removed and reinstalled. Not nearly as bad as the window/door problem.
No my dear friends, do not add drywall to what appears to be the offending surface, the results may end up being truly horrific.
Instead, tear the drywall off the offending surface. At this point solutions become cheaper, quicker, and much more OCD friendly. It may be thinner drywall can be applied. Or that section of the ceiling may need to be rebuilt. Sounds terrible but for a professional this is a short job.
The only thing that might throw a wrench into my beautiful explanation and solution is that there might be a load bearing beam right at that corner. In fact it might be that that corner is bad because nobody wanted to touch the beam that was 1/2" out of place. Removing the drywall would flush up the corner, but we'd have to get clever about covering the beam.
Source: Been there, done that.