From the anonymous fourteenth-century poem Sir Gawain and the Green Knight (Fit I, lines 136-150, trans. Bernard O’Donoghue):
a monstrous apparition strode in the door,
one of the tallest creatures in the whole of the earth.
So square and powerful from neck to waist,
his thighs and his forearms so muscly and long
you’d think that he was some kind of half-giant.
But I think what he was was the hugest of men,
the most pleased with his size of anyone living.
For, though his back and his chest were incredibly big,
his stomach and waist were fashionable trim,
and all his features in proportion, given his size, exactly right.
They were shocked by his colour though,
apparent at first glance;
what was most uncanny was
he was green from head to toe!
Later on in the poem it is revealed that this Green Knight is in fact Lord Bertilak, Gawain’s host, transformed through the magic of Morgan le Fay.
Thus I believe that I have discovered the origins of Marvel’s Incredible Hulk. The Hulk is also entirely green, the monstrous alter ego of a regular human and, when transformed, has a much broader chest than waist (the Hulk’s shirts would always rip off, but never his pants).