LeBron James -- Farewell Letter to Lauren Hill ... 'You'll Never Be Forgotten'

LeBron James just posted a goodbye letter to Lauren Hill -- the 19-year-old college basketball player who died from brain cancer -- explaining how she deeply impacted his life ... even though they never met.

Lauren's story became national news ... when she realized her dream to play for the Mount St. Joseph women's hoops team back in November while battling an inoperable brain tumor.

At the time, James said Hill was "truly amazing" and an inspiration -- and now, with news of her passing, he penned an emotional farewell letter.

"Dear Lauren Hill,

You are the true definition of strength, courage, power, leadership, etc etc! Your time spent on earth will never be forgotten.

I [hate] that I never got the chance to meet u in person but know you inspired me the whole time! For every life u touched, u made the biggest impact of them by just being YOU!!

You're in a far better place now and please don't have too much fun up there w/o all your family and friends.

Can u please tell my Grandma I said hello. Don't be afraid, she knows you cause we spoke about u plenty of times Until we officially meet again, take care and continue to be that LEADER we all love! ‪

#‎RIPLaurenHill