Drop-dead gorgeous describes someone or something so stunning it stops people in their tracks. It's informal and often used for looks, style, outfits, or breathtaking scenery.
In person, if possible, Anubis was even more drop-dead gorgeous. [Oh... ha, ha. I didn't catch the pun, but thank you, Carter. God of the dead, drop-dead gorgeous. Yes, hilarious. Now, may I continue? ]. Rick Riordan
The good thing about not being drop-dead gorgeous is that as time passes, I don't have much to worry about. I have friends who are actors and every day they look in the mirror with trepidation. Moby