People who have the senseless belief that humans are more important than other species.
No dispute that roadrunner cartoons are very good. But Moose and Sqvirrel cartoons are even mo bettah!
As you wish.
People who have the senseless belief that other animals are just as important as people. 
I have a delightfully passive-aggressive way of dealing with these, at least in some circumstances. If I’m not in a hurry (and usually, I’m not), I’ll just walk up and stand behind them (e.g., behind those people at the supermarket blocking the aisle with their carts while they gab) and wait quietly to see how long before they notice me.
Typically, they will eventually notice me and move out of the way, profusely apologizing with much apparent embarrassment. Mission accomplished, thinks I to myself.
People who tell me what things they have cost. Unless I specifically ask you, there is no reason to tell me how much you paid for your new car, your home theatre, your new sweater. I don’t care if you’re trying to point out it was a bargain. Nor is it better when you’re boasting you got it for $2 second hand!
Shut up! Just leave the price tags on all your things and be done with it already.
Every single time you volunteer the price of something you reveal yourself to be an uncultured boor. Stop already!
People with ear gauges are innocent, but I really don’t like them. (I’m fine with tattoos, however).
Snobs of all stripes: beer snobs, coffee snobs, bike snobs, car snobs, career snobs, fitness snobs, etc, etc. You know who I speak of - those that cant resist downplaying your choices and go on about how their selections are superior. f-them.
Me: This beer is pretty good!
Snob: *That’s not “beer” (snicker), it’s crappy IPA - you should be drinking this IPA from this obscure brewery across town where I know the brew master and he uses only hops that come from…
*
Also, “one-uppers” - those that converse with you in a way that they wait for openings where they can out-do you on whatever you just said. These people can just STFU.
Me: This cold I had made me miserable.
One-upper: Oh yeah, did you run a temperature?
Me: I think maybe about 100.
One-upper: Well, MY cold got me up to about 101.
This is a good one! We had a guy in high school who would do it all the time, about anything at all. One of my friends got a kick out of making up stories whenever he was around, just to see what he’d come up with.
intolerant people.
Haters.
I know I know… they gotta hate hate hate hate
But I still hate 'em
Idiot.
My Australian friend told me about a delightful term they have for those people : “black catters” - as in, “My cat is blacker!”
I get the bus to work most days, it’s more or less door-to-door, and it gives me a nice bit of time to read. Even better, my stop is near the start of the route, so it’s rarely busy when I get on in the morning.
What brings me to a flickering moment of incandescent, irrational, rage though is when some innocent is sitting in my fucking seat. 
It doesn’t even happen weekly, but honestly, some people…
I don’t like “those people”.
Barons riding buses? Times really are tough. 
The Baronial business ain’t what it used to be. You just can’t get indentured servants to run the old horse and carriage these days.
Women who sound like children. Not childish diction, just that their voice sounds like the voice of a six year old. I don’t think that it’s deliberate, because they never speak any other way, but it drives me insane and I can’t take them seriously.
Dilbert has an occasionally-appearing co-worker named Topper who does that.
Dilbert cartoons featuring Topper. – Of particular interest.
Similarly, women who think it’s cute to be helpless. Everything must be done for them , because they are princesses who must never muss their hair. Gah, even worse! Women who make everyone wait for hours while they get ready. Nobody gives a flying fuck if your eyeliner is perfect. Let’s go, already!