Thundercracker is a Decepticon. Thundercracker says that the sky is his battle arena and considers himself better than the other beings who cannot leave the ground. He thinks that he is better than them because he can fly and the others wouldn't be able to catch him because can't leave the ground. His superiority is the only thing he feels confident in; but only in his own world. Thundercracker will often attack the beings on the ground that can't fly just to feel even more confident or to satisfy himself. Thundercracker is not all about the evil ways of the Decepticons. Thundercracker sometimes feels sympathy for the humans that he and the Decepticons rein terror on. The only reason that Thundercracker doesn't complain on terrorizing the humans is because he is not confident in telling Megatron about what he feels. The other Decepticons also influence his choice of saying what he feels about reining terror. Thundercracker sure does need reassurance that he is where he is supposed to be, even though his heart is not in the right place.
In the G1 cartoon, Thundercracker was one of Megatrons Elite warriors that participated in the attack on the Ark and in joining the rest of the Transformers in their many million year nap they had under an inactive volcano on Earth. Thundercracker woke up when the rest of the Transformers did and he also took part in trying to gather energon so they could get out of earth.