Odds are the royal gramma but individual temperment varies. I knew of a royal gramma in a friends 150 that would hunt down any hand that was placed in it's tank and attack it and it definitely gave the damsels a run for their money.
For every 1 aggressive royal gramma there are dozens of absolutely docile ones. They're usually a great community fish. Dottybacks are regularly pretty vicious.
DON'T get a dotty back....if i could get mine out i would, for such a little fish so much anger and aggression..
do your self a favour and stay clear of them..