Hal Finney was an Engineer who worked in the computer gaming and cyber security industry. He was a Cryptographic Activist and created the first reusable proof of work system before Bitcoin. On January 10, 2009 he posted the very first tweet about Bitcoin.
Hal Finney was the first person to receive a Bitcoin transaction. Satoshi Nakamoto sent him 10 Bitcoins as a test.
Unfortunately, he passed away in 2014 after being diagnosed with ALS and was cryopreserved by the Alcor Life Extension Foundation.