Steve Gold
British journalist who, with Robert Schifreen, read Prince Philip's Prestel mailbox and got a new law passed as a side effect.
In 1984 Gold and Robert Schifreen got into British Telecom's Prestel viewdata service using a test account whose password was 1234. They worked their way to the Duke of Edinburgh's private mailbox, which made the whole affair impossible to hush up. Both were arrested in 1985 and convicted in 1986 under a 1981 forgery statute.
The Court of Appeal quashed the convictions and the House of Lords upheld the acquittal in 1988: typing in someone else's password simply wasn't forgery. The gap was obvious enough that Parliament passed the Computer Misuse Act in 1990. Gold went on to spend three decades as an IT and security journalist, and died in 2015.