Do you have any wrestlers that come to mind that you totally didn't recognize after not seeing them for many years?
I ask because I was watching the Snuka Dark Side of the Ring and somebody was being interviewed that looked like an aging Dusty Rhodes, although I knew that couldn't be right, of course. I hit pause to try to figure out who it was before the name popped up and I couldn't do it. Turns it out it was Don Muraco.
Bonus points to Droz during the Brawl for All DSofR, but the poor guy is paralyzed and confined to a wheelchair.
It happened recently with Honky Tonk Man, given he looks nothing like his usual self now.
For a more “traditional” answer, I give you the case of Diamond Studd/Razor Ramon, who left me absolutely gobsmacked when I discovered it was actually just Scott Hall with black hair. I know, I know.