Guess The A-Lister in This Sexy Corset!

We're going with a modern take on an old school garment for our latest "Guess Who" ... 'cause our latest star is stunning in a silver corset.

You don't need to know who this star is to tell she's a bona fide supermodel with a body that just won't quit.

This shot comes from when she was getting ready prior to Monday's Met Gala ... when this star threw on her finest clothes before heading out to the biggest party in fashion.

She went solo to the event -- no famous husband by her side ... walking her lonely "rhode" alone.