Gene Spafford
American computer scientist, universally "Spaf", who kept Usenet's group lists in order before becoming one of the leading voices in computer security.
Through the 1980s Spafford posted the monthly lists of active newsgroups that sites relied on to know what officially existed, and he was one of the more visible members of the backbone cabal. The list was effectively Usenet's registry — a job that sounded clerical but quietly determined which discussions survived.
When the Morris worm took down thousands of machines in November 1988, he wrote one of the first technical analyses of how it spread. At Purdue University he founded the COAST security lab in 1992, which grew into the CERIAS research center in 1998. He has been warning against casual security for decades, and has been right rather more often than he has been listened to.