Jørn Lorentzen Cracking Service - a Danish cracker from about 1987 until 1992(?). Cracked many games, about 120.
He wrote a few tools, including the JL-COPY suite of file and disc copying utilities, and also wrote a demo. He was made infamous by NWC's Kill JL Demo.
Jørn Lorentzen is also the author of the Danish book Maskinkode med Amstrad.