Sorry, Terry Bradshaw, Big Ben and Jerome Bettis ... NONE of you are the greatest Steeler of all-time -- so says Rod Woodson, who tells TMZ Sports that honor goes to Mean Joe Greene!
"Man, I'm just thinking Mean Joe," the legendary Pittsburgh defensive back says. "He's so classic!"
It clearly pains Woodson to make the choice -- there are a LOT of candidates ... everyone from Lynn Swann to Franco Harris to Troy Polamalu to Jack Lambert all has a legit claim to the title.