My bearded dragon is being aggressive, anything that comes in or near his tank he tries to attack. If I vacuum near his tank he tries to go after it, when I plug up anything in the socket, if I stick his food in there. For example I have a prepared his pellets and bugs with calcium. And I'll just pour that in his bowl and he tries to attack to container. I'm the only one that can handle him, but it takes a lot of trying. I'm also guessing it's a him I have another one who's a female and about 1 year old who displayed this behavior but not near as bad.
Sometimes during breeding season they can become aggressive (indoor dragons cycles are off so it's possible to trigger breeding mode anytime during the year).