Kaycee Nicole was one of the earliest big internet hoaxes, back in 2000 and 2001 on early blogging platforms, she was presented as a teenage girl blogging about fighting leukemia, and built up a large and genuinely emotionally invested online following. her death was announced in may 2001, which is when things started unraveling, people noticed inconsistencies and eventually traced the whole persona back to a woman in Kansas named Debbie Swenson, who had fabricated the entire thing, including fake photos borrowed from someone else. it predates the term catfish by about a decade but it's basically the same phenomenon.
this basically previewed every future internet hoax playbook, years before catfish was even a word people used
the part that gets me is how many real people got emotionally attached and grieved a person who never existed