I'm curious to know this, because I think there are maybe two that I know of who wear extensive makeup who I recognized without it. And actors whose makeup is minimal(ie Vulcan or Bajoran makeup that doesn't change the appearance of their face much) don't count. We all recognize Leonard Nimoy with or without the ears.
The only two actors I was able to recognize outside of Trek without being told who they were first is Rene Auberjonois and Armin Shimerman.
I recognized Rene because of his nose, his eyes and the general shape of his face(The Odo voice isn't his normal voice, but most of us already know that :P).
I recognized Armin because of the shape of his jaw, mouth and his voice.
Funnily enough, I spotted Armin several times on Stargate: SG-1 ("Oh my God, mom, it's Quark!") and Rene showed up in The Patriot ("Dad, look, it's Odo!"). (I've since seen Rene in other things, but The Patriot was the first time I spotted and recognized him outside of Trek).
I had to see the names to recognize the other actors. To me, Michael Dorn looks COMPLETELY different without Klingon fangs and facial hair. If Worf was clean shaven I might have recognized Michael more easily without makeup.
So, how about the rest of you? Did you ever spot and recognize otherwise heavily made up actors without Trek makeup? (And NO, the DS9 ep Far Beyond The Stars doesn't count, you cheaters