The Jargon File (version 4.4.7, 29 Dec 2003):

true-hacker
 n.

    [analogy with ?trufan? from SF fandom] One who exemplifies the primary
    values of hacker culture, esp. competence and helpfulness to other hackers.
    A high compliment. ?He spent 6 hours helping me bring up UUCP and netnews
    on my FOOBAR 4000 last week ? manifestly the act of a true-hacker.? Compare
    demigod, oppose munchkin.