Susan Headley (born 1959, also known as Susy Thunder or Susan Thunder) was a hacker during the late 1970s and early 1980s. A member of the so-called Cyberpunks, Headley specialized in social engineering, a type of hacking which uses pretexting and misrepresentation of oneself in contact with targeted organizations in order to elicit information vital to hacking those organizations.
Born in Altona, Illinois in 1959, Headley claims to have dropped out of school in the eighth grade after a difficult childhood. She later moved to Los Angeles, California where she worked as a teenage prostitute and was a rock 'n' roll groupie, claiming all four former members of the Beatles among her conquests. She met computer hacker Kevin Mitnick (also known as Condor) in 1980, and together with another hacker, Lewis de Payne (also known as Roscoe), formed a gang of phone phreaks. In The Hacker's Handbook, Headley is referred to as "one of the earliest of the present generation of hackers" and described as successfully hacking the US phone system as a 17-year-old in 1977.
Headley was elected to public office in California in 1994, as City Clerk of California City.