1) People who claim they never have time to do anything, yet can still tell you what happened on every TV show that was on in the last week. This annoys me especially when the person complaining is a writer or another kind of artist. And don't get me started on writers who find time to update their Facebook page every single day but whine that they don't have time to write!
2) People who complain about every ache and pain. If I mentioned every time my lower back felt like someone had ripped out my vertebrae and replaced them with rusty barbed wire, or that my shoulders felt like Atlas had asked me to "hold this a minute" and went for coffee three years ago... yeah, you don't want to hear it and neither do I. Everyone has aches, pains, and bad days. I worked with a woman who had cancer and came to work with a smile and without complaint every day until she went into hospice a week before she died. My headache (and yours) aren't that big of a deal.
3) People who refuse to see the bright side. Yes, bad things happen and usually at the most inopportune time. But if we stop and look at the big picture, we can see that not everything is terrible all at once. It's easy to be focused on the bad, but I try to remind myself to see that there is still good around and try to focus on that instead. It makes it easier to bear the bad stuff.
4) People who believe their way is the only right way. Whether it's how to raise a child, write a book, frost a cake, or whatever it is that I'm currently doing, I always remember that if you ask ten people to clean the floor, they'll probably each do it differently, but in the end, you'll have a clean floor.
I could go on, but another pet peeve of mine is people who complain incessantly, so for now I'll thank you all for listening to me rant and I'll get back to work on what's important!