definatly azula, if it werent for katara zuko and aang would be dead

Azula just loves death!

Azula hello ??? she tottally would love to relish in the murder of anyone but i don't think she would kill someone without her daddy telling her to the whole time she was trying to be the best for her dad

ozie is the firelord if it wasnt for aang the whole world will be dead so its him not azula

If you would then you're a little sick

Azula was mostly doing what she was sent out to do- she was taught all of her life that the Avatar would ruin anything, therefore when the time came, she would have to kill him in order to get him out of the way.

Ozai was taught the same thing, but I don't think it was as heavily shoved at him like it was Azula. He truely is a killer, and the whole Earth Kingdom would have been genocided if Aang didn't step in. It was Azula's idea, of course, but I (personally) think she was getting a little jealous of Zuko getting attention in the meeting, so she stepped in with a plan she figured her father would like.

I don't think Azula would really kill a person if it wasn't about pleasing her father, who was her only parent figure who praised her for her talents.