Then, because he kept this extract in his system for too long, the change ended up being permanent.
However, after he injected himself with a formula to increase his power, he sprouted gray fur and morphed to look animalistic.
Originally in the comics, he looked like a human with oversized hands and feet, which granted him incredible strength and agility.
Eventually Hank’s fur was changed to blue; in real life, the intent was to make Beast’s fur look black, but because the ink looked more blue, eventually the folks at Marvel decided to stick with the azure shading.