Guess Who This Saint Nick Kid Turned Into!

Before this Christmas cutie sitting on Santa's lap would grow up to become a famous fashion model, she was just a little girl celebrating the holidays in L.A.

Though her real name's Jelena, she's known best by her nickname. Her parents are celebs in their own right -- her mom was once a model ... and so are her younger siblings!

After graduating high school -- where she played volleyball and competed in horseback riding -- she moved to NYC to pursue her modeling career ... or revive it, actually.

That's because this young gal started modeling for Baby Guess when she was just 2 years old! She'd return to Guess as an adult and do 3 campaigns with the clothing company.

She'd go on to walk at New York Fashion Week, model for Tom Ford, become a Victoria's Secret Fashion Show mainstay and win International Model of the Year at the British Fashion Awards.