Okay, I might as well join the bandwagon of these riddlers
An animal at large, 12 years on tour
With a stroke or a smile, I set off my roar
In fields of green I stalk my prey
Without any rest, I'll chase for four days
I have many predators, some young and some old
I take them all on at once and take home the gold
All my other foes fall ill at my stare
While I pursue the great golden bear
Pressure means nothing, I'm in everyone's head
They know they're in trouble when they see me in red
When I'm in the hunt, there is no safer bet
My infamous name was that of a vietnam vet.
Who Am I?