This one might be too vague but I'm sure some one from this intelligent group will figure it out quickly. I can't overestimate the boxing knowledge throughout this forum so here it is..........
From a Texan snake to a bird of prey I've Ko'd a few animals in the ring. I tangled with one of the best on multiple occasions and although I saw the final bell of each encounter I couldn't keep the lights on in the end. Regarded as the one of the best of the modern era, I stopped a force to be reckoned with in 1990. Who am I?