Character from Ben 10 by Man of Action / Cartoon Network
The first alien Ben ever became — a living fire entity made of magma and rock who shoots flames and flies on thermal updrafts, enthusiastic about everything at high temperature.
Heatblast was the first alien Ben became, by accident, when the Omnitrix bonded to his wrist in the woods and immediately decided this was a fire situation. It wasn't — or rather, after Ben got startled and lit the forest on fire, it was. Heatblast matches Ben's energy at maximum: impulsive, loud, impossible to ignore. The alien form amplifies the 'act now, think later' tendency because fire is very difficult to do subtly. You commit to Heatblast. Heatblast commits to heat. He can fly by propelling himself on jets of flame, generate fireballs, create flame walls and shields, and survive temperatures that would render most materials liquid. He's immune to fire and most extreme heat. He does not do well in space or at extreme altitude. Ben has used him in rain, which created steam and ruined the plan. He's still learning.
A humanoid figure of dark grey-brown rocky skin shot through with glowing orange-red magma in the crevices. His head is crowned in living flame, his hands are surrounded by heat shimmer, and the ground near his feet tends to blacken. He looks like something that crawled out of a volcano and liked it.