I will begin. I saw the IMDB page of Star Trek: Section 31, where they label the woman Philippa Georgiou as an "emperor" instead of empress. I'm not a perfect English user myself by any means, but even I knew that one!
Well, we're weaning ourselves away from the "-ess" suffix, along with the now archaic "-trix." Amelia Earhart was an "aviatrix" in her day, but now that seems strange, and we commonly use "aviator" for a pilot of either gender. The only time I see the word "actress" is in award ceremonies, and Meryl Streep or Helen Mirren are "actors" in most other contexts. "Negress" went out with the last century, and nobody uses it (or "Negro," for that matter) anymore.
So I would concede that a woman might be an "Emperor" if she ruled in her own right instead of a consort. Not a hill I would care to die on.
Like Louanne, I see the misuse of words like "less" vs. "fewer" and was happy to note that Trader Joe's had a register for "six items or fewer" especially since I had only four items to pay for. (Well, one of them was a dozen eggs, and one would expect a really anal checker to say, "That makes fifteen items, buddy. Go to some other line.")
My own pet peeve is when I refer to people having "free reign" instead of "free rein." I guess emperors can have "free reign" in that their reign is untrammeled, but we give horses "free rein" by dropping the reins and letting the horse go where it wants. Since practically nobody rides horses anymore, it's understandable that some writers don't understand the term.
Writers who say "free rain" should be shot on sight. Also editors who let that slip by them.