This is “Winged Victory of Samothrace.” It is a sculpture of the goddess Nike, unearthed by archeologists in Samothrace, Greece, made by an unknown artist in the Hellenistic period. It is widely considered to be the greatest sculpture ever made, even though pieces of it were lost forever in its excavation.
If someone ever told me that I could spend as much time in The Louvre as I wanted, but I could only ever look at a single piece, it would be this one, in a second.