In the
universe of
Marvel Comics, Annihilus is one of the
arch-enemies of the
Fantastic Four and the ruler of the
Negative Zone.
Annihilus began life more than a thousand years ago as an insect (albeit a smart one, and rather big for a bug) and was beat up a lot by the bullies on his home planet in the Negative Zone.
At one point, he discovered the Seeds of Life and has used them ever since to increase his own strength and intelligence.
Now he fights as a Champion of Evil in a giant metal bug suit, arguably in the giant mechanical suit genre.