Star Wars Costumes - The First Imperial Triangle

The Imperial Mando Commando has a red triangle on his helmet, which is very similar to the one we see on the helmet of Nolan. The earliest stormtrooper designed with a triangle on it that I could find was done by John Molo as a concept work for a new hope. There's also a triangle on the helmet too, but it's a sideways triangle. Oh, look, I got a dirty fingernail right there. That was playing grease monkey earlier today. Out in the garage. So that's an early triangle. But the one that really sticks out as far as like modern Star Wars is from rebels. And so where does that come from? Where does that come