Adam Young
American researcher who described public-key ransomware in 1996, about fifteen years before criminals caught on.
In their 1996 IEEE Security & Privacy paper Cryptovirology, Young and Moti Yung showed how a virus could encrypt a victim's files under the attacker's public key, so that no amount of reverse engineering would recover them. It was meant as a warning. It was read as a manual roughly when cryptocurrency made ransoms easy to collect, and modern ransomware follows the design to the letter.
The pair also coined kleptography: backdoors hidden inside cryptographic algorithms so that only the designer can exploit them. Dual_EC_DRBG later became the textbook case. Their book Malicious Cryptography (2004) collects the work.