Anastasia was the youngest daughter of the last Russian tsar, executed along with her family in 1918. for decades afterward, persistent rumors claimed she'd somehow survived, the most famous claimant was a woman named Anna Anderson, who insisted she was Anastasia from the 1920s until her death in 1984. DNA testing done in the 1990s on preserved samples definitively proved Anderson had no genetic relation to the family at all. the mystery was fully closed out in 2007, when the remains of the two Romanov children missing from an earlier 1991 grave discovery were finally found in a second grave nearby, and DNA testing in 2008 confirmed all family members were accounted for, meaning no child, including Anastasia, actually survived.
the Anna Anderson case ran for like 60 plus years before DNA testing finally shut it down for good, that's a long con or genuine delusion depending how you look at it
kind of a sad ending honestly, especially knowing an entire myth got built on hope that turned out to have zero basis