General Grawl is the (former) main antagonist of Planet 51. He is a high-ranking alien military officer who believes that his planet is under attack from alien invaders (in reality the "invader" is a clueless human astronaut who is no danger to anyone).
Driven by a fear of the unknown General Grawl becomes a menace to himself and his men as well as (somewhat ironically) his world as he becomes obsessed with not only capturing the "alien" but in either killing him or having his brain removed.
However in the end of the film General Grawl is redeemed when he is rescued from his self-destructing base - making him finally realise that the "alien" was not a threat and also opening his eyes to the fact that blind ignorance and fear is far more dangerous than imaginary threats. He was introduced and advertised as the main antagonist, but this was a misinformation campaign made to hide the true main villain.
In Escape from Planet Earth, General Grawl is one of the assistant guard villains allied by Lena and was reworked as a "BASA Guard". He is being commanded to keep Kira and Kip from saving Planet Baab and reaching for Gary. In addition, he is voiced by Joe Sanfelippo.
For more pictures of General Grawl. See General Grawl/Gallery.