Johan "Julf" Helsingius -- Operated the world's most popular anonymous remailer, the Penet remailer (called penet.fi), until he closed up shop in September 1996.
Tsutomu Shimomura -- Shimomura helped catch Kevin Mitnick, the United States' most infamous cracker, in early 1994. He is the co-author of a book about the Mitnick case, Takedown: The Pursuit and Capture of Kevin Mitnick, America's Most Wanted Computer Outlaw-By the Man Who Did It (BooksEnthsiast.com).
Michal Zalewski (lcamtuf) -- prominent security researcher.
5.4 Hacker media personalities
Eric Corley (a.k.a Emmanuel Goldstein) -- Long standing publisher of and founder of the H.O.P.E. conferences. He has been part of the hacker community since the late 70's.