Ninja -- one of the most popular esports stars in the world -- just revealed he has cancer.
The 32-year-old made the announcement on his X page Tuesday evening ... saying that following a routine skin checkup a few weeks back, he was diagnosed with melanoma.
Ninja -- real name Tyler Blevins -- says the problem area was discovered after he had a mole on the bottom of his foot looked at. Thankfully, he said doctors believe it's all in "the early stages," although he's clearly shaken by the diagnosis nonetheless.