Adam Back is a British cryptographer and cypherpunk. In 1997 he proposed Hashcash: to send an email, you had to spend a little computing work, which makes mass spam costly.
The Bitcoin white paper cites Hashcash for its proof of work. Bitcoin uses the same idea, turned into a way to agree on the order of transactions.
Takeaway: Mining builds on an anti-spam idea from the 1990s.