http://culturecrossfire.com/sports/football/jim-brown-80s-comeback/

I recently wrote a piece on Jim Brown's feud with Franco Harris. Harris was on the verge of besting Brown's NFL career rushing record, and Brown was not pleased by Harris' meek running style. Brown went so far as to lobby to be allowed to play for the Raiders. Eventually, he and Harris ended up competing in a four event competition which aired in syndication on Super Bowl weekend of 1985.

Other notables:
Reggie White - I'll never forget the image of White as a Panther, being passed up during running drills by the massive Sean Gilbert.
Lyle Alonzo - A comeback attempt at 40 went badly.
Johnny Unitas as a Charger.
Joe Namath trotting out as a Ram for 4 games.
Brett Favre's final year in Minnesota, where he ended his ironman career by being pummeled into a mass of rubble, never to take another snap.

Who do you have to add?
Several boxers and MMA fighters definitely belong in this category.

nolan ryan should have quit one season sooner than he did

There's very few guys who go out on top. I don't have any problem with them trying until the game tells them they can't compete anymore.
Peyton Manning went out on a high note. The guy is a total class act. He knew when it was time to go. And he's got a brilliant career to look back on.

"It's better to burn out... than fade away..."

Peyton Manning went out on a high note. The guy is a total class act. He knew when it was time to go. And he's got a brilliant career to look back on.

"It's better to burn out... than fade away..."

I totally agree! ;):wave: Not only a fantastic athlete and quarterback but a good guy and a family man!;) He doesn't act like he is a famous multi millionaire , he seems like a guy that could be your neighbor!! A very down to earth, modest, nice guy ;) He really puts the word Man in the name Manning ! He's the Man! :D Perfect last name for him! ;)