In my opinion, there are several that I would like to cut their head off and making disappear for ever; the first one in my list is Maven, in second place I would say vamps in general, third, Legate Rikke ( she treats our dragonborn like a common soldier even though he is promoted to Legate, the same rank she holds ) and then, in general, all of the Jarls; they are just nasty. The Jarl of Whiterun treat you well when he is in need of you but if he is not, he treats the dragonborn like a common citizen. And last but not the least, the freaking idiot Orc in Solsthein that bill you for a debt that you really do not owe. I paid him and immediately turned to sneaking mode and cut his f ... neck off !! Simply annoying and arrogant and I can stand that.
In general, in Skyrim there is not respect and appreciation for the dragonborn. They have the tendency to forget that you saved them from Alduin, the Vamps and Miraak and even if you sided with the Imperials, they continue disrespecting you and treat you bad.
I agree to the other that Ancano is an idiot, arrogant-alien-face-type-with-pig-ears-shape that deserve a lesson, but he is a bad guy from always so you know what to expect from him, but not from people that you have helped and still treat you like a piece of s... Just my 2 cents .. like Spartacus said : “kill them all” ...