Is there a ransomware for Windows 9X?

Ransomware specifically wasn't really a thing back then because there weren't many ways to anonymously receive money from victims. The earliest one I know is the AIDS DOS virus, which would run on DOS but technically it can also run on 9x machines in DOS mode. Except the "ransom" in this case would be sending cash in an envelope to a P.O. Box in Panama. The original code also isn't that destructive as the virus only renames system files, which can also be decrypted using the decryption key in the source code.

If you only want to completely destroy the computer, then I'd say the Lorie worm is pretty interesting.