The other "Iron" man is Mike Landrum -- a former professional fighter who claims he coined the nickname "Iron Mike" before he turned pro in 1983. Tyson started fighting professionally in 1985.
Landrum has filed a lawsuit in federal court in Los Angeles, claiming he owns the trademark to the nickname "Iron Mike" -- and therefore, Tyson infringed on his rights by using the nickname throughout his boxing career.
Landrum -- who's representing himself in the case -- tells us he was "hindered from getting any major title fights or sponsorships because of the name confusion."
For the record -- Landrum's record was 6-4 as a pro.
TMZ spoke with Tyson's rep Tammy Brook who tells us, "Mike's legal team hasn't seen the paperwork yet, but they are confident the case holds no merit."